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 Italian city of Venice was one of the largest cities in medieval and Renaissance era Europe. It was the center of the Republic of Venice, a maritime empire in the Mediterranean, and had one of Europe's largest ports for exotic goods (particularly from Asia), or luxury goods such as glassware. Impact of plague While its population was relatively small by modern standards, it is believed that Venice was among the five most populous cities in Western Europe in the given years between 1050 and 1650. The city's population did fluctuate over time due to devastating pandemics, and it is believed that Venice was one of the main points of entry for the Black Death in Europe. Venice was one of the hardest-hit cities during the Black Death; estimates fluctuate greatly across sources, but it is believed that the city lost around 40 percent of its population during the initial outbreak in the 1340s. Decline Furthermore, Venice lost roughly a third of its population during further plague pandemics (both introduced via war) in the 1570s and 1630s. Because of this, the population was kept fairly consistent across the given years between 1600 and 1800. The 18th century also saw the decline of the Venetian Empire, as other states gained power and influence in the Mediterranean. Venice also lost its importance as the entry point of exotic goods into Europe, as other European powers had already established their own maritime empires and trade routes across the globe. Eventually, the crumbling Venetian Empire fell to Napoleon in 1796, and its overseas territories were gradually taken by or split among various other powers. While the empire fell, the city itself continued to be a center for art and culture in Europe, and it has maintained this status until today. In 2021, Venice had a population of more than 250,000 people.

Throughout the early modern period, the largest city in Italy was Naples. The middle ages saw many metropolitan areas along the Mediterranean grow to become the largest in Europe, as they developed into meeting ports for merchants travelling between the three continents. Italy, throughout this time, was not a unified country, but rather a collection of smaller states that had many cultural similarities, and political control of these cities regularly shifted over the given period. Across this time, the population of each city generally grew between each century, but a series of plague outbreaks in the 1600s devastated the populations of Italy's metropolitan areas, which can be observed here. Naples At the beginning of the 1500s, the Kingdom of Naples was taken under the control of the Spanish crown, where its capital grew to become the largest city in the newly-expanding Spanish Empire. Prosperity then grew in the 16th and 17th centuries, before the city's international importance declined in the 18th century. There is also a noticeable dip in Naples' population size between 1600 and 1700, due to an outbreak of plague in 1656 that almost halved the population. Today, Naples is just the third largest city in Italy, behind Rome and Milan. Rome Over 2,000 years ago, Rome became the first city in the world to have a population of more than one million people, and in 2021, it was Italy's largest city with a population of 2.8 million; however it did go through a period of great decline in the middle ages. After the Fall of the Western Roman Empire in 476CE, Rome's population dropped rapidly, below 100,000 inhabitants in 500CE. 1,000 years later, Rome was an important city in Europe as it was the seat of the Catholic Church, and it had a powerful banking sector, but its population was just 55,000 people as it did not have the same appeal for merchants or migrants held by the other port cities. A series of reforms by the Papacy in the late-1500s then saw significant improvements to infrastructure, housing, and sanitation, and living standards rose greatly. Over the following centuries, the Papacy consolidated its power in the center of the Italian peninsula, which brought stability to the region, and the city of Rome became a cultural center. Across this period, Rome's population grew almost three times larger, which was the highest level of growth of these cities.