During the period of the Northern and Southern Courts, the Ii clan was in rivalry with Suruga no kuni shugo (provincial constable of Suruga Province) Imagawa clan, but eventually, the Ii clan was put under the control of the Imagawa clan after the Imagawa clan was appointed to the position of shugo of Totomi Province.
南北朝時代には駿河国守護今川氏と対立していたが、やがて今川氏が遠江国の守護職を得るとその支配下に置かれる。