In 1435 his father Tokihiro died and in 1437 he was defeated in an uprising in Bingo by his brother, Mochihiro YAMANA, who was unhappy that Mochitoyo had inherited the family headship.
1435年には父の時熙が死去し、1437年には兄弟の山名持熙が持豊の家督相続に不満を持ち備後で挙兵し、これを鎮圧する。