Mogami clan
Much of Dewa Province was controlled by the powerful Mogami clan during the Sengoku period. After Toyotomi Hideyoshi assigned the Uesugi clan to Aizu, senior Uesugi retainer Naoe Kanetsugu established himself at the neighboring Yonezawa Domain, with an army of 20,000 and gradually expanded his control north into Mogami territory. However, with the help of the Date clan under Date Masamune, the Mogami were able to defend Yamagata until Naoe was forced to withdraw following the defeat of the pro-Toyotomi forces at the Battle of Sekigahara.