筑前國
The Koremune extended its influence on Tsushima over the course of the Kamakura period, as the deputies of the Shōni. When the Mongols invaded Japan in 1274, clan head Sō Sukekuni fought against the invaders and died on Tsushima. The Sō clan fought for the Shōni clan and for the Ashikaga Northern Court during the Nanboku-chō period (1336–1392), and seized a portion of Chikuzen Province. Imagawa Ryōshun became "Chinzei Tandai" (head of the Dazaifu government) soon afterwards, and the Imagawa clan became "shugo" of Tsushima. When Imagawa Ryōshun was dismissed from his post in 1395, Sō Sumishige became "shugo" of Tsushima.