East Thrace the Turkish Straits) and the Sea of Marmara, a route of about 361 km. The southernmost part of Eastern Thrace is called the Gallipoli peninsula. European Turkey is bordered on the west by Greece for 212 km and on the north by Bulgaria for 269 km, with the Aegean Sea to the south-west and the Black Sea to the north-east. East Thrace was the setting for several important events in history and legend. The mass killings and displacement of Thracian Bulgarians in 1913 and the 1923 population exchange between Greece and Turkey ethnically cleansed the Orthodox populations. Prior to that
Geography of Turkey of the sizable Greek-speaking community of western Turkey were forced to resettle in Greece, while the majority of the Turkish-speaking residents of Thrace who were not forced out during the Balkan wars were removed to Turkey. The boundary with Bulgaria was confirmed by the Treaty of Lausanne (1923). Since 1991 the more than boundary with the former Soviet Union, which was defined in the 1921 Treaty of Moscow (1921) and Treaty of Kars, has formed Turkey's borders with the independent countries of Armenia, Azerbaijan, and Georgia. The boundary with Iran was confirmed by the Treaty of Kasr-ı Şirin in 1639.