The Mogami were a Japanese samurai clan which existed from 1360 to 1614. Ashikaga scion Kaneyori Shiba built Yamagata Castle in 1360, and Kaneyori took the surname "Mogami" after a town in Dewa Province. For the first half of the 16th century, the Mogami were dominated by the Date clan, but, in 1542, the civil war in the Date clan enabled Yoshimori Mogami to gain independence from the Date. Yoshiaki Mogami expanded his clan's territory enormously, and his death in 1614 ended the clan's rule.