In 1517, Tsunehisa partnered with the former Iwami shugo, the Yamana clan, who was not satisfied with the appointment of Yoshioki OUCHI as Iwami shugo, and the two clans attacked a castle of the Iwami-Ouchi clan.
永正14年（1517年）、大内義興の石見守護就任に納得出来なかった前石見守護山名氏と手を結び、石見大内方の城を攻めている。