Treaty of Kyehae
The Kyehae Treaty was signed in 1443 between the Joseon and the Sō clan head Sadamori as a means of controlling wokou and legitimizing trade between Tsushima and three Korean ports. It is also called Kakitsu Treaty; 1443 is the third year of the Kakitsu era in the Japanese calendar. The treaty was the last document signed between Japan and Korea for 433 years till 1876.
Precedents
Tsushima was then an important trade center. The private trade started between Goryeo, Tsushima, Iki, and Kyūshū, but halted during the Mongol invasions of Japan between 1274 and 1281. The Goryeosa, a history of Goryeo, reports that in 1274, a Mongol army that included many Korean soldiers killed many Japanese on the islands.Tsushima became one of the major bases for the wokou, along with the Iki and Matsuura. Repeated pirate raids led Goryeo, and subsequently Joseon, to placate pirates by establishing trade agreements and negotiating with the Ashikaga shogunate and its deputy in Kyūshū, as well as using force to neutralize them. In 1389, General Pak Wi of Goryeo attempted to clear Tsushima of wokou, but uprisings in Korea forced him to return home.
On June 19, 1419, the recently abdicated King Taejong of Joseon sent General Yi Chongmu to an expedition to Tsushima to clear it of wokou, using a fleet of 227 vessels and 17,000 soldiers known in Japanese as the Ōei Invasion. The army returned to Korea on July 3, 1419, and Korea gave up occupation of Tsushima. In 1443, the Daimyo of Tsushima, Sō Sadamori proposed a Kyehae treaty. The number of ships permitted to trade between Tsushima and Korea was determined by this treaty, and the Sō clan monopolized trade with Korea.