U´lai a river which flowed by Susa [SHUSHAN] into the united stream of the Tigris and Euphrates. It is mentioned in . It is called by Pliny Eulaeus, but is described by Greek writers under the name of Choaspes, and is now known by the name of Kerah, called by the Turks Karasu. This river is formed by the junction of many streams in the province of Ardelan, in Kurdistan. It runs through the plain of Kermanshah, and being greatly increased in magnitude by the junction of two small rivers, proceeds with a furious course towards Khuzistan, receiving numerous tributaries in its passage. It passes on the west of the ruins of Shus [Susa: see SHUSHAN], and enters the Shat-ul-Arab about twenty miles below Korna.