The Sumbar (also Sari-su, Sara-su and Ṣáríṣú) is a fast flowing river in southern Turkmenistan and northern Iran.
The name Sari-su means yellow water in Turkic languages, but is applied to a number of other rivers as well.
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 the latter by a range of hills called the Marábeh.
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