An ancient kingdom, the origin and early history of which is uncertain, between the Niphates Mountains of Armenia on the N. and Babylonia on the S., 280 m. long and 150 broad, with a fertile soil and a population at a high stage of civilisation; became a province of Media, which lay to the E., in 606 B.C., and afterwards a satrapy of the Persian empire, and has been under the Turks since 1638, in whose hands it is now a desert.