Sargon of Akkad (c. 2340-2285 B.C.E.) defeated Lugalzagesi of Uruk in battle, thereby unifying Sumer and Akkad. Sargon then established his capital in his own city-state of Akkad. All Akkadian kings faced a continual threat from the Guti, who were tribal nomadic people living around the Diyala river valley and the Zagros mountain range. The Guti succeeded in diminishing the Akkadian Empire, after which time there was a short-lived dynasty founded by Ur-nigin of Uruk.