The world's population first reached one billion people in 1805, and reached eight billion in 2022, and will peak at almost 10.2 billion by the end of the century. Although it took thousands of years to reach one billion people, it did so at the beginning of a phenomenon known as the demographic transition; from this point onwards, population growth has skyrocketed, and since the 1960s the population has increased by one billion people every 12 to 15 years. The demographic transition sees a sharp drop in mortality due to factors such as vaccination, sanitation, and improved food supply; the population boom that follows is due to increased survival rates among children and higher life expectancy among the general population; and fertility then drops in response to this population growth. Regional differences The demographic transition is a global phenomenon, but it has taken place at different times across the world. The industrialized countries of Europe and North America were the first to go through this process, followed by some states in the Western Pacific. Latin America's population then began growing at the turn of the 20th century, but the most significant period of global population growth occurred as Asia progressed in the late-1900s. As of the early 21st century, almost two-thirds of the world's population lives in Asia, although this is set to change significantly in the coming decades. Future growth The growth of Africa's population, particularly in Sub-Saharan Africa, will have the largest impact on global demographics in this century. From 2000 to 2100, it is expected that Africa's population will have increased by a factor of almost five. It overtook Europe in size in the late 1990s, and overtook the Americas a few years later. In contrast to Africa, Europe's population is now in decline, as birth rates are consistently below death rates in many countries, especially in the south and east, resulting in natural population decline. Similarly, the population of the Americas and Asia are expected to go into decline in the second half of this century, and only Oceania's population will still be growing alongside Africa. By 2100, the world's population will have over three billion more than today, with the vast majority of this concentrated in Africa. Demographers predict that climate change is exacerbating many of the challenges that currently hinder progress in Africa, such as political and food instability; if Africa's transition is prolonged, then it may result in further population growth that would place a strain on the region's resources, however, curbing this growth earlier would alleviate some of the pressure created by climate change.

Between 1800 and 2021, the total population of each continent experienced consistent growth, however as growth rates varied by region, population distribution has fluctuated. In the early 19th century, almost 70 percent of the world's population lived in Asia, while fewer than 10 percent lived in Africa. By the end of this century, it is believed that Asia's share will fall to roughly 45 percent, while Africa's will be on course to reach 40 percent. 19th and 20th centuries Fewer than 2.5 percent of the world's population lived in the Americas in 1800, however the demographic transition, along with waves of migration, would see this share rise to almost 10 percent a century later, peaking at almost 14 percent in the 1960s. Europe's share of the global population also grew in the 19th century, to roughly a quarter in 1900, but fell thereafter and saw the largest relative decline during the 20th century. Asia, which has consistently been the world's most populous continent, saw its population share drop by the mid-1900s, but it has been around 60 percent since the 1970s. It is important to note that the world population has grown from approximately one to eight billion people between 1800 and the 2020s, and that declines in population distribution before 2020 have resulted from different growth rates across the continents. 21st century Africa's population share remained fairly constant throughout this time, fluctuating between 7.5 and 10 percent until the late-1900s, but it is set to see the largest change over the 21st century. As Europe's total population is now falling, and it is estimated that the total populations of Asia and the Americas will fall by the 2050s and 2070s respectively, rapid population growth in Africa will see a significant shift in population distribution. Africa's population is predicted to grow from 1.3 to 3.9 billion people over the next eight decades, and its share of the total population will rise to almost 40 percent. The only other continent whose population will still be growing at this time will be Oceania, although its share of the total population has never been more than 0.7 percent.

Until the 1800s, population growth was incredibly slow on a global level. The global population was estimated to have been around 188 million people in the year 1CE, and did not reach one billion until around 1803. However, since the 1800s, a phenomenon known as the demographic transition has seen population growth skyrocket, reaching eight billion people in 2023, and this is expected to peak at over 10 billion in the 2080s.

In 1800, the region of present-day Switzerland had a population of approximately 1.8 million people. This figure would grow steadily throughout the 19th century, as political and religious grievances gave way to a united federation, whose economic policies saw Switzerland emerge as one of Europe's most prosperous and stable countries. Growth boomed between 1890 and 1910, as industrialization would see significant economic growth and migration to the country. While Switzerland’s neutrality in both World Wars would prevent the mass fatalities experienced across the rest of Europe during the early 20th century, Switzerland’s population would nevertheless stagnate in both the First and Second World War and in the Great Depression in the 1930s, as the economic turmoil and conflict abroad would halt the migration that had previously driven population growth.

Following the end of the Second World War, growth would resume and would rise steadily until the late 1970s, before an economic recession saw the population fall again as workers migrated in search of employment elsewhere. However, population growth has steadily risen since the 1980s, reaching seven million in the mid-1990s and eight million in 2012. Today, with a population of 8.7 million, Switzerland is ranked among the wealthiest and most developed nations in the world, with very high standards of living.

In 1800, the population of Yemen was just under 2.6 million, and would gradually grow to just 3.2 million by the end of the 18th century. Between the mid-1800s and early-1900s, the north and south regions of present-day Yemen had been split into territories of the British and Ottoman empires respectively; the north became independent in 1918, during Ottoman dissolution, while the British did not withdraw from the region until 1967. Yemen would experience an exponential growth in population in the years beginning in the 1970s, following the discovery of petroleum in the country, though this would slow somewhat in the 1990s, in part the result of food shortages and instability throughout the country years following the unification of South Yemen and the Yemen Arab Republic. In 2020, the population of Yemen is estimated to be just under thirty million people, however, the country has been experiencing a civil war in since 2015, which has resulted in one of the most severe humanitarian crises in recent history, with over 100,000 deaths (mostly children, due to famine) as well as the displacement of millions of people, and one of the most severe cholera outbreaks in recent decades.

In 1800, the population of the area of modern-day Slovakia was estimated to be just over two million, a figure which would grow steadily throughout the 19th century as part of the kingdom of Hungary and later under the dual kingdom of Austria-Hungary. This growth would continue even throughout the first half of the 20th century, as the country would largely escape conflict in both the First and Second World Wars. As a result, Slovakia’s population would rise to just under three and a half million by 1950.

Slovakia’s population would begin to rapidly increase in the years following the Second World War, however, as the country would experience both a baby boom and large-scale modernization and industrialization as part of the Czechoslovak Socialist Republic. After slowing somewhat in the late 1960s, population growth would increase once more in the 1970s and 1980s, as Slovakia would become the first of the Soviet republics to begin the “normalization” process of reforms brought about by the Soviet perestroika (restructuring) movement. While population growth would largely flatline following the dissolution of the Soviet Union in 1991, unlike many former Soviet republics who saw their populations decline as net emigration rose, Slovakia’s population has managed to avoid declining, and in the 2010s, has even begun to rise again. As a result, in 2020, Slovakia is estimated to have a population of just under five and a half million.

In 1800, the present-day region of Mexico had a population of just over six million people. Mexico gained its independence from the Spanish crown in 1821, and population growth remained steady for the next 85 years. Growth then halted with with the Panic of 1907, an American financial crisis whose ripple effects in Mexico would set the stage for the Mexican Revolution in 1910. This revolution would see population flatline at just over fifteen million between 1910 and 1920, as widespread conflict and result in the death of between 1.7 to 2.7 million over the decade, and the coinciding 1918 Spanish Flu epidemic would see the loss of another 300,000 in this time period. Following the end of both the Mexican Revolution and the Spanish Flu epidemic in 1920, the population of Mexico would begin to increase rapidly as modernization would see mortality rates fall and standards of living rise throughout the country. This growth has continued steadily into the 21st century, and in 2020, Mexico is estimated to have a population of just under 129 million.

In the past four centuries, the population of the Thirteen Colonies and United States of America has grown from a recorded 350 people around the Jamestown colony in Virginia in 1610, to an estimated 346 million in 2025. While the fertility rate has now dropped well below replacement level, and the population is on track to go into a natural decline in the 2040s, projected high net immigration rates mean the population will continue growing well into the next century, crossing the 400 million mark in the 2070s. Indigenous population Early population figures for the Thirteen Colonies and United States come with certain caveats. Official records excluded the indigenous population, and they generally remained excluded until the late 1800s. In 1500, in the first decade of European colonization of the Americas, the native population living within the modern U.S. borders was believed to be around 1.9 million people. The spread of Old World diseases, such as smallpox, measles, and influenza, to biologically defenseless populations in the New World then wreaked havoc across the continent, often wiping out large portions of the population in areas that had not yet made contact with Europeans. By the time of Jamestown's founding in 1607, it is believed the native population within current U.S. borders had dropped by almost 60 percent. As the U.S. expanded, indigenous populations were largely still excluded from population figures as they were driven westward, however taxpaying Natives were included in the census from 1870 to 1890, before all were included thereafter. It should be noted that estimates for indigenous populations in the Americas vary significantly by source and time period. Migration and expansion fuels population growth The arrival of European settlers and African slaves was the key driver of population growth in North America in the 17th century. Settlers from Britain were the dominant group in the Thirteen Colonies, before settlers from elsewhere in Europe, particularly Germany and Ireland, made a large impact in the mid-19th century. By the end of the 19th century, improvements in transport technology and increasing economic opportunities saw migration to the United States increase further, particularly from southern and Eastern Europe, and in the first decade of the 1900s the number of migrants to the U.S. exceeded one million people in some years. It is also estimated that almost 400,000 African slaves were transported directly across the Atlantic to mainland North America between 1500 and 1866 (although the importation of slaves was abolished in 1808). Blacks made up a much larger share of the population before slavery's abolition. Twentieth and twenty-first century The U.S. population has grown steadily since 1900, reaching one hundred million in the 1910s, two hundred million in the 1960s, and three hundred million in 2007. Since WWII, the U.S. has established itself as the world's foremost superpower, with the world's largest economy, and most powerful military. This growth in prosperity has been accompanied by increases in living standards, particularly through medical advances, infrastructure improvements, clean water accessibility. These have all contributed to higher infant and child survival rates, as well as an increase in life expectancy (doubling from roughly 40 to 80 years in the past 150 years), which have also played a large part in population growth. As fertility rates decline and increases in life expectancy slows, migration remains the largest factor in population growth. Since the 1960s, Latin America has now become the most common origin for migrants in the U.S., while immigration rates from Asia have also increased significantly. It remains to be seen how immigration restrictions of the current administration affect long-term population projections for the United States.

In 1800, the population of Indonesia was estimated to be approximately 16 million. The population of the island nation would grow steadily over the course of the 19th century, as the Dutch colonial administration launched several initiatives to modernize the region. After reaching 38 million people in 1900, the population of Indonesia would continue to grow until the 1940’s, when the Japanese occupation of the country would see between four to ten million Indonesians moved away from the island nation to be made to work on Japanese military projects, and in combination with wartime famine, this would result in the death or displacement of up to four million Indonesians by the end of the Japanese occupation in 1945. Despite this, Indonesia's population continued to grow throughout these years.

Following the Second World War, Indonesia claimed its independence from the Netherlands, and achieved this in 1949. In the second half of the 20thcentury, the population would continue to grow exponentially in size through the remainder of the 20th century, although the growth rate would slow somewhat in the 1980s, the result of a decline in fertility rate throughout the country which some studies suggest may be attributed to improved access to birth control and improved mass education. In 2020, Indonesia is estimated to have just over 273.5 million people living within its borders, making it the fourth most populous country in the world (behind the U.S. and above Pakistan).

The history of modern Brazil begins in the year 1500 when Pedro Álvares Cabral arrived with a small fleet and claimed the land for the Portuguese Empire. With the Treaty of Torsedillas in 1494, Spain and Portugal agreed to split the New World peacefully, thus allowing Portugal to take control of the area with little competition from other European powers. As the Portuguese did not arrive with large numbers, and the indigenous population was overwhelmed with disease, large numbers of African slaves were transported across the Atlantic and forced to harvest or mine Brazil's wealth of natural resources. These slaves were forced to work in sugar, coffee and rubber plantations and gold and diamond mines, which helped fund Portuguese expansion across the globe. In modern history, transatlantic slavery brought more Africans to Brazil than any other country in the world. This combination of European, African and indigenous peoples set the foundation for what has become one of the most ethnically diverse countries across the globe.

Independence and Monarchy By the early eighteenth century, Portugal had established control over most of modern-day Brazil, and the population more than doubled in each half of the 1800s. The capital of the Portuguese empire was moved to Rio de Janeiro in 1808 (as Napoleon's forces moved closer towards Lisbon), making this the only time in European history where a capital was moved to another continent. The United Kingdom of Portugal, Brazil and the Algarves was established in 1815, and when the Portuguese monarchy and capital returned to Lisbon in 1821, the King's son, Dom Pedro, remained in Brazil as regent. The following year, Dom Pedro declared Brazil's independence, and within three years, most other major powers (including Portugal) recognized the Empire of Brazil as an independent monarchy and formed economic relations with it; this was a much more peaceful transition to independence than many of the ex-Spanish colonies in the Americas. Under the reign of Dom Pedro II, Brazil's political stability remained relatively intact, and the economy grew through its exportation of raw materials and economic alliances with Portugal and Britain. Despite pressure from political opponents, Pedro II abolished slavery in 1850 (as part of a trade agreement with Britain), and Brazil remained a powerful, stable and progressive nation under Pedro II's leadership, in stark contrast to its South American neighbors. The booming economy also attracted millions of migrants from Europe and Asia around the turn of the twentieth century, which has had a profound impact on Brazil's demography and culture to this day.

The New Republic

Despite his popularity, King Pedro II was overthrown in a military coup in 1889, ending his 58 year reign and initiating six decades of political instability and economic difficulties. A series of military coups, failed attempts to restore stability, and the decline of Brazil's overseas influence contributed greatly to a weakened economy in the early 1900s. The 1930s saw the emergence of Getúlio Vargas, who ruled as a fascist dictator for two decades. Despite a growing economy and Brazil's alliance with the Allied Powers in the Second World War, the end of fascism in Europe weakened Vargas' position in Brazil, and he was eventually overthrown by the military, who then re-introduced democracy to Brazil in 1945. Vargas was then elected to power in 1951, and remained popular among the general public, however political opposition to his beliefs and methods led to his suicide in 1954. Further political instability ensued and a brutal, yet prosperous, military dictatorship took control in the 1960s and 1970s, but Brazil gradually returned to a democratic nation in the 1980s. Brazil's economic and political stability fluctuated over the subsequent four decades, and a corruption scandal in the 2010s saw the impeachment of President Dilma Rousseff. Despite all of this economic instability and political turmoil, Brazil is one of the world's largest economies and is sometimes seen as a potential superpower. The World Bank classifies it as a upper-middle income country and it has the largest share of global wealth in Latin America. It is the largest Lusophone (Portuguese-speaking), and sixth most populous country in the world, with a population of more than 210 million people.

Throughout the 19th century, what we know today as Poland was not a united, independent country; apart from a brief period during the Napoleonic Wars, Polish land was split between the Austro-Hungarian, Prussian (later German) and Russian empires. During the 1800s, the population of Poland grew steadily, from approximately nine million people in 1800 to almost 25 million in 1900; throughout this time, the Polish people and their culture were oppressed by their respective rulers, and cultural suppression intensified following a number of uprisings in the various territories. Following the outbreak of the First World War, it is estimated that almost 3.4 million men from Poland served in the Austro-Hungarian, German and Russian armies, with a further 300,000 drafted for forced labor by the German authorities. Several hundred thousand were forcibly resettled in the region during the course of the war, as Poland was one of the most active areas of the conflict. For these reasons, among others, it is difficult to assess the extent of Poland's military and civilian fatalities during the war, with most reliable estimates somewhere between 640,000 and 1.1 million deaths. In the context of present-day Poland, it is estimated that the population fell by two million people in the 1910s, although some of this was also due to the Spanish Flu pandemic that followed in the wake of the war.

Poland 1918-1945

After more than a century of foreign rule, an independent Polish state was established by the Allied Powers in 1918, although it's borders were considerably different to today's, and were extended by a number of additional conflicts. The most significant of these border conflicts was the Polish-Soviet War in 1919-1920, which saw well over 100,000 deaths, and victory helped Poland to emerge as the Soviet Union's largest political and military rival in Eastern Europe during the inter-war period. Economically, Poland struggled to compete with Europe's other powers during this time, due to its lack of industrialization and infrastructure, and the global Great Depression of the 1930s exacerbated this further. Political corruption and instability was also rife in these two decades, and Poland's leadership failed to prepare the nation for the Second World War. Poland had prioritized its eastern defenses, and some had assumed that Germany's Nazi regime would see Poland as an ally due to their shared rivalry with the Soviet Union, but this was not the case. Germany invaded Poland on September 1, 1939, in the first act of the War, and the Soviet Union launched a counter invasion on September 17; Germany and the Soviet Union had secretly agreed to do this with the Molotov-Ribbentrop Pact in August, and had succeeded in taking the country by September's end. When Germany launched its invasion of the Soviet Union in 1941 it took complete control of Poland, which continued to be the staging ground for much of the fighting between these nations. It has proven difficult to calculate the total number of Polish fatalities during the war, for a variety of reasons, however most historians have come to believe that the figure is around six million fatalities, which equated to almost one fifth of the entire pre-war population; the total population dropped by four million throughout the 1940s. The majority of these deaths took place during the Holocaust, which saw the Nazi regime commit an ethnic genocide of up to three million Polish Jews, and as many as 2.8 million non-Jewish Poles; these figures do not include the large number of victims from other countries who died after being forcefully relocated to concentration camps in Poland.

Post-war Poland

The immediate aftermath of the war was also extremely unorganized and chaotic, as millions were forcefully relocated from or to the region, in an attempt to create an ethnically homogenized state, and thousands were executed during this process. A communist government was quickly established by the Soviet Union, and socialist social and economic policies were gradually implemented over the next decade, as well as the rebuilding, modernization and education of the country. In the next few decades, particularly in the 1980s, the Catholic Church, student groups and trade unions (as part of the Solidarity movement) gradually began to challenge the government, weakening the communist party's control over the nation (although it did impose martial law and imprison political opponent throughout the early-1980s). Increasing civil unrest and the weakening of Soviet influence saw communism in Poland come to an end in the elections of 1989. Throughout the 1990s, Poland's population growth stagnated at around 38.5 million people, before gradually decreasing since the turn of the millennium, to 37.8 million people in 2020. This decline was mostly due to a negative migration rate, as Polish workers could now travel more freely to Western Europea...

In 1800, the population of the region making up present-day Croatia was just over 1.2 million. Croatia's population grew relatively consistently throughout the 19th and early 20th centuries, despite the region suffering around 200,000 fatalities in each of the World Wars. The lack of clearly defined boundaries, mass displacement and general disorganization have made it very difficult for historians to estimate the total number of fatalities suffered by Croatia and by ethnic Croats in this time; additionally, the various ethnic groups within Yugoslavia at the time committed a number of atrocities against one another, which has exacerbated this.

In spite of these events, the population of Croatia would continue to grow steadily until the early 1990s, when it was one of six parts of the Socialist Federative Republic of Yugoslavia. In the wake of communism's demise in Southern Europe in the late 20th century, Croatia claimed its sovereignty in 1991, which set in motion the Croatian War of Independence with Serbia. War was waged for four years, and saw the deaths of more than 20,000 people, while several hundred thousand were displaced. In the quarter century since the war's end, Croatia has emerged as a high-income, developing country, with a booming tourism and hospitality industry. However the population has continued to drop as a result of declining birth rates, and large-scale economic migration (particularly influenced by the financial crisis of 2008 and Croatia's accession to the European Union in 2013).

In 1800, the region of Germany was not a single, unified nation, but a collection of decentralized, independent states, bound together as part of the Holy Roman Empire. This empire was dissolved, however, in 1806, during the Revolutionary and Napoleonic eras in Europe, and the German Confederation was established in 1815. Napoleonic reforms led to the abolition of serfdom, extension of voting rights to property-owners, and an overall increase in living standards. The population grew throughout the remainder of the century, as improvements in sanitation and medicine (namely, mandatory vaccination policies) saw child mortality rates fall in later decades. As Germany industrialized and the economy grew, so too did the argument for nationhood; calls for pan-Germanism (the unification of all German-speaking lands) grew more popular among the lower classes in the mid-1800s, especially following the revolutions of 1948-49. In contrast, industrialization and poor harvests also saw high unemployment in rural regions, which led to waves of mass migration, particularly to the U.S.. In 1886, the Austro-Prussian War united northern Germany under a new Confederation, while the remaining German states (excluding Austria and Switzerland) joined following the Franco-Prussian War in 1871; this established the German Empire, under the Prussian leadership of Emperor Wilhelm I and Chancellor Otto von Bismarck. 1871 to 1945 - Unification to the Second World War The first decades of unification saw Germany rise to become one of Europe's strongest and most advanced nations, and challenge other world powers on an international scale, establishing colonies in Africa and the Pacific. These endeavors were cut short, however, when the Austro-Hungarian heir apparent was assassinated in Sarajevo; Germany promised a "blank check" of support for Austria's retaliation, who subsequently declared war on Serbia and set the First World War in motion. Viewed as the strongest of the Central Powers, Germany mobilized over 11 million men throughout the war, and its army fought in all theaters. As the war progressed, both the military and civilian populations grew increasingly weakened due to malnutrition, as Germany's resources became stretched. By the war's end in 1918, Germany suffered over 2 million civilian and military deaths due to conflict, and several hundred thousand more during the accompanying influenza pandemic. Mass displacement and the restructuring of Europe's borders through the Treaty of Versailles saw the population drop by several million more.

Reparations and economic mismanagement also financially crippled Germany and led to bitter indignation among many Germans in the interwar period; something that was exploited by Adolf Hitler on his rise to power. Reckless printing of money caused hyperinflation in 1923, when the currency became so worthless that basic items were priced at trillions of Marks; the introduction of the Rentenmark then stabilized the economy before the Great Depression of 1929 sent it back into dramatic decline. When Hitler became Chancellor of Germany in 1933, the Nazi government disregarded the Treaty of Versailles' restrictions and Germany rose once more to become an emerging superpower. Hitler's desire for territorial expansion into eastern Europe and the creation of an ethnically-homogenous German empire then led to the invasion of Poland in 1939, which is considered the beginning of the Second World War in Europe. Again, almost every aspect of German life contributed to the war effort, and more than 13 million men were mobilized. After six years of war, and over seven million German deaths, the Axis powers were defeated and Germany was divided into four zones administered by France, the Soviet Union, the UK, and the U.S.. Mass displacement, shifting borders, and the relocation of peoples based on ethnicity also greatly affected the population during this time. 1945 to 2020 - Partition and Reunification In the late 1940s, cold war tensions led to two distinct states emerging in Germany; the Soviet-controlled east became the communist German Democratic Republic (DDR), and the three western zones merged to form the democratic Federal Republic of Germany. Additionally, Berlin was split in a similar fashion, although its location deep inside DDR territory created series of problems and opportunities for the those on either side. Life quickly changed depending on which side of the border one lived. Within a decade, rapid economic recovery saw West Germany become western Europe's strongest economy and a key international player. In the east, living standards were much lower, although unemployment was almost non-existent; internationally, East Germany was the strongest economy in the Eastern Bloc (after the USSR), though it eventually fell behind the West by the 1970s. The restriction of movement between the two states also led to labor shortages in t...

In 1800, the population of the territory that makes up present-day Thailand was approximately 4.7 million people. As part of the kingdom of Siam, the population of Thailand would grow gradually through the 19 th century, with much of the population growth being driven by Chinese emigration from southern Qing China into Siam, in search of work and refuge from instability in their home country. This migrant influx would continue throughout the century, with estimates suggesting that the Chinese population in Siam grew from 230,000 in 1825, to over 792,000 in 1910; by 1932, over 12 percent of the population in modern-day Thailand was ethnically Chinese. Migration from China would see another surge under the reign of Vajiravudh, as the "Warlord era" in China, after the fall of the Qing dynasty, would see entire families of Chinese immigrants arriving in Thailand. While immigration would slow in later years, Chinese-Thai would remain a significant demographic in Thailand’s population, both as one of the largest overseas Chinese populations, and accounting for an estimated 11-14 percent of the total Thailand population in 2012.

Population growth would slow somewhat in the 1930s, as several rebellions and coups, paired with a rise in anti-Chinese sentiment in the country, would result in a sharp decline in immigration to the country. In the years following the Second World War, the population of Thailand would begin to grow rapidly, following a wave of urbanization and a significant increase in standard of living throughout the country. As a result, the population of Thailand would rise from approximately 20 million in 1950, to just under 63 million by the turn of the century just 50 years later. This population growth would slow somewhat as the country would continue to modernize in the 2000s, and in 2020, it is estimated that just under 70 million people live in Thailand.

In 1800, the population of the region that makes up present-day Ecuador was approximately half a million people. This figure would begin to grow following Ecuador’s breakaway from the Spanish empire, first into the state of Gran Colombia in 1822, and then as its own fully independent republic in 1830. The Ecuadorian population would grow slowly but steadily throughout the 19th century, and by 1900, the country would have just under one and a half million people. Beginning in the 1930s, however, population growth would begin to increase more and more rapidly, as reforms and modernization programs begun under José María Velasco Ibarra would allow for an increasingly large population to be supported. As a result, Ecuador’s population would triple from a little over two million in 1930, to over six million in 1970. This growth would remain steady well into the 21st century, and in 2020, Ecuador is estimated to have a population of approximately 17.6 million.

In 1800, the population of Japan was just over 30 million, a figure which would grow by just two million in the first half of the 19th century. However, with the fall of the Tokugawa shogunate and the restoration of the emperor in the Meiji Restoration of 1868, Japan would begin transforming from an isolated feudal island, to a modernized empire built on Western models. The Meiji period would see a rapid rise in the population of Japan, as industrialization and advancements in healthcare lead to a significant reduction in child mortality rates, while the creation overseas colonies would lead to a strong economic boom. However, this growth would slow beginning in 1937, as Japan entered a prolonged war with the Republic of China, which later grew into a major theater of the Second World War. The war was eventually brought to Japan's home front, with the escalation of Allied air raids on Japanese urban centers from 1944 onwards (Tokyo was the most-bombed city of the Second World War). By the war's end in 1945 and the subsequent occupation of the island by the Allied military, Japan had suffered over two and a half million military fatalities, and over one million civilian deaths.

The population figures of Japan were quick to recover, as the post-war “economic miracle” would see an unprecedented expansion of the Japanese economy, and would lead to the country becoming one of the first fully industrialized nations in East Asia. As living standards rose, the population of Japan would increase from 77 million in 1945, to over 127 million by the end of the century. However, growth would begin to slow in the late 1980s, as birth rates and migration rates fell, and Japan eventually grew to have one of the oldest populations in the world. The population would peak in 2008 at just over 128 million, but has consistently fallen each year since then, as the fertility rate of the country remains below replacement level (despite government initiatives to counter this) and the country's immigrant population remains relatively stable. The population of Japan is expected to continue its decline in the coming years, and in 2020, it is estimated that approximately 126 million people inhabit the island country.

The earliest point where scientists can make reasonable estimates for the population of global regions is around 10,000 years before the Common Era (or 12,000 years ago). Estimates suggest that Asia has consistently been the most populated continent, and the least populated continent has generally been Oceania (although it was more heavily populated than areas such as North America in very early years). Population growth was very slow, but an increase can be observed between most of the given time periods. There were, however, dips in population due to pandemics, the most notable of these being the impact of plague in Eurasia in the 14th century, and the impact of European contact with the indigenous populations of the Americas after 1492, where it took almost four centuries for the population of Latin America to return to its pre-1500 level. The world's population first reached one billion people in 1803, which also coincided with a spike in population growth, due to the onset of the demographic transition. This wave of growth first spread across the most industrially developed countries in the 19th century, and the correlation between demographic development and industrial or economic maturity continued until today, with Africa being the final major region to begin its transition in the late-1900s.

The state of Belgium owes its name to Julius Caesar, who used the name "Belgium" to refer to the region in his narrative "The Gallic Wars". After the fall of the Western Roman Empire, the region emerged as a cosmopolitan trading center, and was a collection of smaller duchies and states (such as Flanders and Brabant), before modern history saw control of the region pass between France, the Netherlands and (to a lesser extent) Spain. Modern day Belgium emerged in 1830 following the Belgian Revolution when it gained independence from the Kingdom of the Netherlands. Throughout this time, the Belgian region was the setting of many conflicts between other European powers, which greatly affected the population development and demography of the area. From 1800 until the First world War, the population of Belgium grew steadily, and more than doubled in the nineteenth century. The World Wars Population growth stagnated in the 1910s, as a result of World War I and the Spanish Flu epidemic. Belgium was one of the focal points of military action in the war, and many military personnel from other nations also lost their lives here during the conflict. Much of the Second World War also took place in Belgium, and although it remained neutral at the outbreak of both wars, it was invaded twice by Germany due to its strategic importance. Belgium suffered an estimated 88,000 fatalities during the war; with many further military fatalities from other nations also perishing in the region. Continuous growth From 1950 onwards, Belgium's population grows at a relatively consistent rate, to more than ten million people the year 2000. Since the turn of the millennium, a positive net migration rate and higher life expectancy has meant that Belgium's population has grown even faster rate than in the twentieth century. Today, Belgium has a very high standard of living, and the capital city of Brussels is home to the headquarters of many international institutions, particularly the European Union.

In 1800, the region of present-day Peru had a population of approximately 1.3 million people. Growth was slow at the beginning of the 19 th century. However, following Peru’s breakaway from the Spanish empire in 1824, the population would begin to slowly increase, and would nearly triple by the turn of the 20th century to approximately 3.7 million. This growth would expand exponentially in the mid-1900s, particularly during the global baby boom in the 1950s and 1960s, as an increase in fertility combined with decreases in child mortality led to rapid growth of the increasingly urbanizing population. This growth would slow somewhat between 1995 and 2013, a slowdown in part attributed to a large-scale expansion of family planning services in the country. However, the last decade has seen an increase in the rate of population growth in Peru, as the country has been one of the main destinations for Venezuelan refugees; with over 600,000 refugees residing in the country as of 2019. As a result, by 2020, almost 33 million people are estimated to live in the country.

In 1800, the population of Spain was approximately 14.7 million. This figure would rise consistently throughout the 19th century, and early 20th century. The population growth rate was set to increase in the mid-1900s, but this was interrupted by the Spanish Civil War, which would claim around half a million lives between 1936 and 1939. In spite of the war, the Spanish population continued to grow throughout these years, and reached 28 million by the middle of the century. Between the 1950s and 1970s, Spain observed a significant increase in its population growth, facilitated by the baby boom that followed the Second World War (as in most of Western Europe) as well as general medical improvements and increased life expectancy.

Beginning in the 1980s, Spain would begin a demographic transition marked by a dramatic drop in the fertility rate of the country, resulting in the population only growing by two million between the mid-1980s and 2000 (compared to an increase of two million every five or six years beforehand). There was a sharp rise in Spain’s population from 2000 to 2008, as strong economic growth would be accompanied by a dramatic surge in immigration to the country. This would plateau at just over 46 million in 2008 however, as the Great Recession took its toll on the country’s economy, and in 2020, Spain is estimated to have a population of approximately 46.8 million, which is the sixth-largest in Europe.