In 1800, the region of modern-day North Macedonia had a population of approximately 392,000. The population grew steadily throughout the 19th century, and reached approximately 800,000 by the beginning of the 20th century. During this time the region was under Ottoman control, and was something of an ethnic melting pot, with significant shares of the population made up of Macedonians, Greeks, Turks, as well as other Slavic groups. The early-1900s saw control of the region pass between various powers, as the Ottoman Empire fell and gave way to a power vacuum in the Balkans. Following the Second World War, North Macedonia became a part of Yugoslavia; the war's end would also see a baby boom, along with increased population growth throughout the second half of the 20th century.

The gradual dissolution of Yugoslavia in the early 1990s gave way to the establishment of an independent Macedonia in 1991. This time also saw much emigration from the region, both within the former-region of Yugoslavia, as well as abroad; international migration was largely driven by economic factors, especially due to those associated with independence, as well as those associated with the strained political relationship with Greece. Disputes with Greece over the terms "Macedonia", "Macedonians", and their cultural significance, resulted in Greece blocking the country's applications to join the EU and NATO. Non-membership of both these organizations prevented the country from obtaining the associated socio-economic benefits for decades, before a referendum was held in 2018 to officially change the name to the "Republic of North Macedonia". Since this time, Greece has withdrawn its objections to North Macedonia's accession to the the EU and NATO, and the relationship between the two has improved. North Macedonia became a member of NATO in March 2020, however disputes with Bulgaria arose in November of the same year, which have further delayed accession to the EU. Over the past two decades, North Macedonia's population has grown, although it has remained fairly constant at just over two million people.

Bulgaria, with the help of the Russian Empire, achieved independence from the Ottoman Empire in 1878. In the decades before independence, Bulgaria's population had remained between 2.2 and 2.8 million people, and growth was much slower then the following century. Although most at the time assumed that it would become a Russian ally, Bulgaria defied the expectations and aligned itself with the western powers, and developed into a modern European state by the turn in the late 1800s. Bulgaria at war In the early twentieth century Bulgaria was involved in both World Wars, as well as two Balkan Wars. The Balkan states were unhappy with the borders assigned to them by the western powers, and instead wanted to re-draw them based on the dispersal of ethnic groups. This led to the first Balkan War in 1912, which saw Bulgaria fight alongside Greece and Serbia against the Ottomans. Bulgaria fought the second Balkan War on all sides, this time against Greece, Serbia, Romania and the Ottomans, as the dispute over borders continued. Bulgaria was defeated this time, and sustained heavy casualties, amassing in 58 thousand fatalities and over 100 thousand wounded in the two wars.

In the First World War, Bulgaria remained neutral at first, in order to recover from the previous wars, but then aligned itself with the Central powers in 1915, and played a vital role in maintaining their control in the Balkans. While Bulgaria was initially successful, its allies weakened as the war progressed, and then Bulgaria eventually succumbed to Allied forces and surrendered in 1918, with almost 200 thousand Bulgarians dying as a result of the war. The interwar years was a period of political and economic turmoil, and when control was re-established, Bulgaria was then able to maintain it's neutrality throughout most of the Second World War, (although there was some conflict and bombings in certain areas). Rise and fall of communism After the war, Bulgaria became a communist state, and life became harsh for the civil population there until the late 1950s when the standard of living rose again. In the late 1980s, like many Eastern European countries, Bulgaria experienced economic decline as the communist system began to collapse. Political failures also contributed to this, and approximately 300 thousand Bulgarian Turks migrated to Turkey, greatly weakening the agricultural economy. This trend of mass migration abroad continued after the fall of the iron curtain, as well as the rise of unemployment. Bulgaria reached it's peak population size in 1985 at 8.98 million inhabitants, but then the number decreases each year, and is expected to be 6.94 million in 2020. This drop in population size has been attributed to the economic collapse at the end of communism in Eastern Europe, causing many to leave the country in search of work elsewhere. Bulgaria also has one of the lowest fertility rates in the world, with 8.7 births per 1,000 people per year (in 2018).