Cyaxares (sīăk´sərēz), d. 585 BC, king of Media (c.625–585 BC). His name also appears as Umakishtar and Huyakhshtara. In the course of his reign he raised the kingdom of the Medes to a major power in the Middle East. Cyaxares reorganized Median military forces, developing the cavalry especially, and renewed war with Assyria. He captured and leveled (614) Ashur and after joining forces with Nabopolassar of Babylonia as well as with the Scythians, who were former enemies, besieged Nineveh, occupying and pillaging the city in 612. Fighting continued (612–605) in N Mesopotamia and ended in the defeat of the Assyrians, with Cyaxares claiming Assyria proper as Media's share of the spoils. Hostilities later erupted between Media and the neighboring kingdom of Lydia in the northwest; they lasted from 590 to 585, ending in a stalemate. Cyaxares was succeeded by his son Astyages.