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
Thrace (theme) Krum (r. 803–814), Omurtag (r. 814–831), and Symeon (r. 893–927) the border moved by stages south of the Balkan mountains to roughly the line of the present Bulgarian frontier with Greece and Turkey. Thus, at around the start of the 10th century, the theme comprised essentially the eastern half of modern Eastern Thrace, although it extended north along the coast to include Anchialos. From the 11th century, Thrace and Macedonia appear to have been usually combined, as attested by numerous "strategoi" and judges ("kritai") holding jurisdiction over both themes. The name fell out of use as an administrative term in