Sampo Waeran

The Three ports incident, is known as 'ko:삼포왜란' in Korea and (三浦の乱 (Sanbo-No-Ran) in Japan.

Summary
At the beginning of the Joseon dynasty, due to the frequent attacks by foreign powers, the Korean government adopted an isolationist foreign policy and stationed troops near the port of Busan to enforce it. From 1407 to 1426, the Korean government modified this policy by gradually opening several ports to trade with Japan. By 1426 three ports were open to Japanese trade: Busan, Naei, and Yeom. During this time, the number of Japanese residents of Korea surpassed 2000. The local Japanese government on Tsushima island assumed responsibility for governing these Japanese citizens, and exported cotton grown in Korea to Tsushima Island. Local farmers who owned the land on which the cotton was grown wanted to collect taxes on the cotton, but the Korean government, in an attempt to improve foreign relations with Japan, decided to exempt the Japanese from being taxed on the cotton. When King Jungjong of Joseon succeeded his half-brother King Yeonsangunof Joseon to the throne, the Korean government implemented reforms that included ending tax breaks for Japanese citizens. As a result of the new taxes, Japanese citizens experienced increased economic hardship and petitioned the Japanese government on Tsushima Island for relief. Japan had ships off the Korean coast to enforce laws and provided military support to Japanese citizens living in Korea. In April of 1510, two Japanese men, Obarishi and Yasko, led between 4000 and 5000 men in an attack on Busan, Naei, Yeom, and the castle located at Naei. A military general stationed at Busan, U-Jeung Lee (李友曾), was killed and the leader at the Naei port, Sae-Gyun Kim (金世鈞), was kidnapped. Dam-Nyeon Yu (柳聃年) and Hyeong Hwang (黃衡) were immediately sent by the Korean government to suppress the riots. As a result, the son of the governor of Tsushima Island was killed and the riots were subdued.

Results
As a result of the riots, over 270 Koreans were killed or injured, 796 homes were destroyed, 295 Japanese people were killed, and 5 Japanese ships were sunk. The Joseon government sent relief to people living in the affected regions and deported all remaining Japanese people to Tsushima Island. When the dead from the riots were buried, the graves of the Japanese were marked differently, to warn future visitors to Korea of the consequences of participating in riots. After the riots, all commercial activity between the two countries ended. This negatively affected the Japanese people living on Tsushima Island and Japanese citizens demanded a re-opening of the ports. In response to this demand, in 1512 the emperor of Japan publicly punished the leader of Tsushima Island, who was responsible for causing the riots in Korea, and repatriated Korean prisoners of war that had been living in Japan. Koreans accepted this peace offering from the Japanese emperor and the two countries entered into the ImSin Agreement (壬申約條) or the Agreement of 1512. The agreement reopened the port at Naei to commercial activity; however, the number of Japanese ships and citizens allowed in Korea remained lower than before the riots.