An important tributary of the Euphrates River in eastern Syria. Its basin was a strategic area for communications between Mesopotamia, Syria, and Anatolia (Turkey), and it contains such important sites as Tell Halaf, Chagar Bazar, and Tell Brak. It has given its name to a distinctive painted ware found in northern Mesopotamia and north Syria in the early 2nd millennium BC. Pottery of this type also occurs at Kultepe in Anatolia, indicating wide-ranging trade at the time.