The Ii were originally from Tôtômi Province and claimed descent from Fujiwara Yoshikado (ca.850). During the early Sengoku period they fought with the Imagawa in cooperation with Shiba Yoshisato but later became Imagawa vassals. The Ii became powerful under Tokugawa Ieyasu thanks to Ii Naomasa, one of the Ieyasu's four most famous generals, and were politically influential until the end of Edo period.