Syria–Turkey border

The border between the Syrian Arab Republic and the Republic of Turkey is about 822 kilometres (511 mi) long. It runs across Upper Mesopotamia for some 400 km, crossing the Euphrates reaching as far as the Tigris, following the Southern Turkish stretch of the Baghdad Railway roughly along the 37th parallel between the 37th and 42nd eastern meridians. In the west, it surrounds the Turkish Hatay Province, following the course of the Orontes River and reaching the Mediterranean coast at the foot of Jebel Aqra.

The current Syro-Turkish border was established in the Partitioning of the Ottoman Empire after World War I, based on the Sykes–Picot Agreement between United Kingdom and France in 1916. It was the northern border of the State of Aleppo and later the State of Syria during the 1920s, and the Syrian Republic followed by the short-lived United Arab Republic during the 1930s to 1950s and since 1961 has been the border between the modern states of Syria and Turkey.

The approximate line of most of the border was set by the Treaty of Ankara in 1921. It was delimited more precisely between Meidan Ekbis and Nusaybin in 1926, and between Nusaybin and the tripoint with Iraq in 1929. A special case is the Turkish Hatay Province, which remained autonomous until 1923, then became part of Syria as the Sanjak of Alexandretta (Franco-Syrian Treaty of Independence (1936)), briefly became independent as the Hatay State in 1938 before being annexed by Turkey as the Hatay Province in 1939. The new international border was demarcated by a Franco-Turkish commission in 1938/9, with a protocol of 3 May 1939 mentioning 448 boundary markers placed in numerical order, and an additional protocol signed in Antioch on 19 May 1939 mentioning some additional markers. Some further changes were made in an agreement signed in Ankara on 23 June 1939.

...
Wikipedia