Sumbar River

The Sumbar (also Sari-su, Sara-su and Ṣáríṣú) is a fast flowing river in southern Turkmenistan and northern Iran. It a tributary of the Atrek. The name Sari-su means "yellow water" in Turkic languages, but is applied to a number of other rivers as well. It used to be an area for Caspian tigers in Turkmenistan, until the last individual was killed in January 1954.
Geography.
The Sumbar is long and drains a basin of . It arises in the Kopet Dag 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 .