The Sumbar is a fast flowing river in southern Turkmenistan

Turkmenistan

Turkmenistan , formerly also known as Turkmenia is one of the Turkic states in Central Asia. Until 1991, it was a constituent republic of the Soviet Union, the Turkmen Soviet Socialist Republic . Turkmenistan is one of the six independent Turkic states...

 and northern Iran

Iran

Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...

. It a tributary of the Atrek

Atrek

The Atrek is a fast-moving river which begins in the mountains of Northeastern Iran , and flows westward draining into the southeastern corner of the Caspian Sea in Turkmenistan...

. The name Sari-su means yellow water in Turkic languages, but is applied to a number of other rivers as well.

Geography

The Sumbar is 245 km long and drains a basin of 8300 km². It arises in the Kopet Dag

Kopet Dag

The Kopet Dag, Kopet Dagh, or Koppeh Dagh , also known as the Turkmen-Khorasan Mountain Range is a mountain range on the frontier between Turkmenistan and Iran, extending about 650 km along the border, east of the Caspian Sea. The highest peak of the range in Turkmenistan is southwest of the...

mountains in Iran and flows into Turkmenistan. For a long stretch before the Sumbar runs into the Atrek, it is separated from it by a range of hills called the Marábeh. The Atrek becomes the Turkmenistan-Iran border where the Sumbar flows into it, at 37°59′28"N 55°16′29"E.