Bulgaria, with a long and rich Slavonic history, was notable for its medieval empires; it fell under Ottoman rule in 1396. Although independent after 1878, instability persisted into the 20th century, and after World War II Bulgaria was part of the Soviet block, emerging in 1990 with its first multi-party elections. The principal ethnic group is Bulgarian, with a minority of Turkish, and Roma inhabitants; together they share common historic roots in Thracian, Roman, Slavonic, Ottoman, and Romanian cultures.
The country has pronounced landscapes (the Balkan and Rhodope mountain ranges, the Danube River plain, and the Black Sea coast) that are important factors in the development of the different types of vernacular architecture still found.