The Aras is a river in the Caucasus. It rises in eastern Turkey and flows along the borders between Turkey and Armenia, between Turkey and the Nakhchivan exclave of Azerbaijan, between Iran and both Azerbaijan and Armenia, and, finally, through Azerbaijan where it flows into the Kura river. It drains the south side of the Lesser Caucasus Mountains while the Kura drains the north side of the Lesser Caucasus. The river's total length is 1,072 km (666 mi) and its watershed covers an area of 102,000 km2 (39,000 sq mi). The Aras is one of the longest rivers in the Caucasus.

The Caucasus, or Caucasia, is a transcontinental region between the Black Sea and the Caspian Sea, mainly comprising Armenia, Azerbaijan, Georgia, and parts of Southern Russia. The Caucasus Mountains, including the Greater Caucasus range, have historically been considered as a natural barrier between Eastern Europe and West Asia.