The 1877-78 Russo-Turkish war that liberated Bulgaria ended in the Treaty of San Stefano, which reestablished a Bulgarian kingdom using the ancient boundaries; but the treaty was never put into effect because the European powers feared a large Russian client-state in the Balkans. Meeting in the Congress of Berlin in 1878, the powers nullified the Treaty of San Stefano and decreed Bulgarian boundaries that drastically reduced the size of the newly liberated country. Bulgaria seethed with irredentism and fought wars over the so-called lost territories until World War II, from which it emerged with a communist-dominated coalition government but confined to almost the same boundaries. After the Communists took complete control, irredentism was overshadowed by Marxist ideas of internationalism; but the dream of a greater Bulgaria did not die, and irredentist opinions were commonly expressed until 1972, when they were muted, probably on the insistence of the Soviet Union.
The original Bulgars were of an Asian tribe that moved into the Balkan Peninsula as conquerors during the seventh century A.D. The occupants of the area at the time were mostly Slavs who had been migrating to that region for more than a century, absorbing former inhabitants as they settled. Within about two centuries of their conquest, the Bulgars also had been completely absorbed by the much more numerous Slavs, leaving only their name to mark the land they had conquered. From the ninth century A.D. on, Bulgarian history is the story of this amalgamated nation of Bulgar-Slavs who enjoyed two different epochs of independent glory under medieval Bulgarian kingdoms but who also suffered invasion and defeat and, eventually, 500 years of domination by Ottoman Turks. In 1878 Turkish rule was finally ended, and a truncated Bulgaria reappeared on the map of Europe. After five centuries of foreign domination, Bulgaria was backward, underdeveloped, and poor.
The descendants of the Bulgar-Slavs made up the majority of the approximately 8.7 million people living in Bulgaria in 1973. The largest minority group, which numbered about 0.7 million people, was Turkish. The few Greeks, Romanians, Armenians, and Jews in the population collectively accounted for only about 1 percent of the total. These modern Bulgarians live in a country that is almost rectangular in shape and covers roughly 42,800 square miles of the lower Balkan Peninsula. Their country is bounded on the east by the Black Sea, on the south by Greece and the part of Turkey that is in Europe, on the west by Yugoslavia, and on the north by Romania.