river in Afghanistan and Turkmenistan, formed by the confluence of two headstreams, the Āq Robāţ and the Galleh Chaghar, which rise in northwestern Afghanistan. The river flows northwestward, passing the town of Koshk-e Kohneh (Kushk), where it turns north and receives the waters of the Moqor (Jōye Ḏaṟāb); for 10 miles (16 km) it forms the Turkmenistan-Afghanistan border. The river then turns northeast into Turkmenistan, where it receives the Egriyok River and eventually empties into the Morghāb River near Dashköpri after a course of 172 miles (277 km). It drains a basin of about 4,100 square miles (10,700 square km). The river is completely dry in portions of its course during the summer months, but its waters irrigate farmlands along its middle and lower courses. The region through which the river flows is semiarid.