In the July 1419, King Taejo sent a letter to Tsushima's Sō Sadamori laying claim to the historical repossession of Daemado (Tsushima) due to the Korean victory in war. Once again the land was Korean territory as it had been under the Kingdom of Silla. An arrangement was proposed for Tsushima to enter into a tributary relationship. In the 9th month of 1419 Sadamori sent an emissary to surrender the territory and to present a variety of tribute to the Korean court. In January 1420, a Japanese envoy visiting Seoul requested to have a copy of Tripitaka Koreana, a comprehensive Buddhist script held in great regard as a Korean national treasure. King Sejong granted the request as sign of friendship between two countries. In the 1st leap month of 1420 Sadamori requested that the island officially become a state of Korea under the name of Daemado, also promising to personally become a subject and to manage the Wokou situation as an independent act of the state. King Sejong granted this request as well as allowing Sadamori to report to Gyeongsang province rather than Seoul.