Balkan States, or Balkans, the countries occupying the Balkan Peninsula in southern Europe. They consist of Albania, Serbia and Montenegro, Bosnia and Herzegovina, Croatia, Slovenia, Romania, Bulgaria, the European part of Turkey, Greece, and the Republic of Macedonia. Adjoining the peninsula are the Black Sea, the Sea of Marmara, and several arms of the Mediterranean, including the Aegean, Ionian, and Adriatic seas. The Balkans have an area of roughly 305,000 square miles (790,000 km2)—somewhat more than that of Texas.

Mountains ranging up to 10,000 feet (3,000 m) high and rough, hilly lands make up most of the terrain. (The word Balkan stems from a Turkish word meaning “mountain.") Lowlands and plains lie mainly along the coasts and in the valleys of the major rivers, which include the Danube, Sava, Morava, Vardar, and Maritsa. Climate varies from a continental type with hot summers and cold winters in the north to the mild Mediterranean type in the south.

The Balkans have been the least developed and most impoverished part of Europe for centuries. Only since World War II have most of the Balkan nations begun to industrialize and to modernize their agricultural methods.

The main ethnic groups in the Balkans are the Slavs (Serbs, Croats, Slovenes, and Bulgarians); Romanians; Turks; Albanians; and Greeks. The Greeks and Albanians are the oldest groups. Some of the people belong to the Eastern Orthodox faith, some are Roman Catholics, and some are Muslims. The population of the Balkan Peninsula in 1985 was about 72,500,000.