Query: How long did the Soviet Union retain a hegemonic role?
Context: The main focus was in the Balkans where the South Slavs had been ruled for centuries by other empires: the Byzantine Empire, Austria-Hungary, the Ottoman Empire, and Venice. The Russian Empire used Pan-Slavism as a political tool; as did the Soviet Union, which gained political-military influence and control over most Slavic-majority nations between 1945 and 1948 and retained a hegemonic role until the period 1989–1991.