Azerbaijan–Türkiye border
A few miles of the Aras river where Türkiye touches Nakhchivan, Azerbaijan’s exclave. Fixed in 1921, it now carries a gas pipeline, and a railway is being built to it.
Written from cited sourcesLast checked 29 September 2026Suggest a correction
See it on the globe:Azerbaijan →Türkiye →
A Soviet frontier on the Aras
Russia pushed south into the Caucasus in the 19th century and took the plain of Erivan from Persia in 1828, making the Aras river the Russo-Persian border. After World War I, Türkiye moved its border back north: the Treaty of Aleksandropol of 2 December 1920 gave it a southern slice of the old Russian province of Erivan, bringing the line north to the Aras.[1]
The Soviet–Turkish Treaty of Moscow of 16 March 1921 and the Treaty of Kars of 13 October 1921 confirmed the line, and a mixed commission marked it in 1925–26. It has not changed since.[1] In its last 8½ miles, before the Iranian border meets it at the mouth of the Kara Su, the line along the Aras separates Türkiye from the Nakhchivan Autonomous Republic, part of Soviet Azerbaijan.[1][2]
A lifeline for Nakhchivan
Nakhchivan is an exclave, separated from mainland Azerbaijan by southern Armenia.[3] In March 2025 the two countries opened an 80 km gas pipeline from Iğdır in Türkiye, built by the state companies BOTAŞ and SOCAR, with capacity to meet the gas needs of all of Nakhchivan.[4]
In August 2025 Türkiye broke ground on a 224 km railway from Kars through Iğdır to the Dilucu border gate, to connect with Nakhchivan’s railway. Turkey’s transport minister said it should be finished in four to five years and would form part of a route through southern Armenia to mainland Azerbaijan agreed in a US-brokered peace deal that month.[3]
Timeline
1828
Treaty of Turkmenchay
Russia takes the Erivan plain; the Aras becomes the Russo-Persian border.[1]
19202 December 1920
Treaty of Aleksandropol
Türkiye gains land south of the Aras.[1]
192113 October 1921
Treaty of Kars
The Moscow treaty’s line is confirmed.[1]
1925–26
Demarcation
A mixed commission marks the Soviet–Turkish border.[1]
2025March 2025
Gas pipeline
The Iğdır–Nakhchivan pipeline opens.[4]
2025August 2025
Railway begun
Work starts on the Kars–Dilucu line.[3]
More borders
Sources
- [1]International Boundary Study No. 29: Turkey – U.S.S.R. Boundary · US Department of State, Office of the Geographer · 24 February 1964
- [2]International Boundary Study No. 28: Iran – Turkey Boundary · US Department of State, Office of the Geographer · 1964
- [3]Türkiye starts building rail link to Nakhchivan, key to Zangezur Corridor · Daily Sabah · 2025-08
- [4]Igdır-Nakhchivan natural gas pipeline opens · Anadolu Agency · 2025-03
Map geometry from Natural Earth via world-atlas. See credits.