Thrace, a historic region and ancient country in the Balkan Peninsula, at the head of the Aegean Sea. The area is now divided among northeastern Greece, southern Bulgaria, and the European part of Turkey. In ancient times the region was settled by several tribes of Thracians, a people of the Indo-European language family. After 700 B.C. the Greeks established colonies along the Thracian coast. Thrace was conquered and held by Persia, 512–479 B.C. After the Thracians had regained independence, they were united into a kingdom by Teres, a tribal chief. Thrace came under the control of Macedonia in 342 B.C.
From the second century B.C. until the 14th century A.D. Thrace was, for most of the time, ruled by Rome and by the Byzantine Empire, which succeeded Rome in eastern Europe. However, other powers were sometimes able to control the Thracian region for brief periods. During the 14th and 15th centuries Thrace was absorbed into the Ottoman Empire. Bulgaria acquired northern Thrace by action of the Congress of Berlin in 1878 and by annexation in 1885; it was awarded western Thrace after the Balkan Wars (1912–13). The present national boundaries within the region were set in the Treaty of Lausanne (1923).