The earliest ancestor of the clan is said to be Mochimori OUCHI, the second son of Yoshihiro OUCHI, who rebelled against the third Muromachi shogun, Yoshimitsu ASHIKAGA, in the Oei War.
祖先は応永の乱で室町幕府第3代将軍・足利義満に反乱を起こした大内義弘の次男・大内持盛と言われている。