Joseon subsequently asked the Ashikaga shogunate and its deputy in Kyūshū to suppress pirate activity, favoring legitimate traders. In exchange for certain privileges, it gave authority to Sō Sadashige (the de facto ruler of Tsushima Province) over ships sailing from Japan to Korea. When Sō Sadashige died in 1418, power was seized from Sadashige's infant son Sadamori (Tsutsukumaru) by Soda Saemontaro, a powerful pirate leader. Suffering from famine, pirates on Tsushima invaded Ming China in 1419. On the way to China, they invaded Korea's Bi-in and Haeju country after their demands for food were rejected.