Sambyeolcho Rebellion 삼별초의 난 三別抄-亂
Unlike other rebels, Sambyeolcho had assumed the reins of Goryeo government before the rebellion. They were private armies of the Choe family, who had maintained a military dictatorship. When the Mongols invaded Goryeo, Choes' military government under the nominal king fled to Ganghwado Island in 1232 and resisted the Mongol invasion. Unfortunately because of its fragile foundation Goryeo faced frequent rebellions. Some of them were crushed by the government, but the rebels in the northern area defected to the Mongols and their areas were annexed to the Mongol Empire. Eventually the military government was overthrown in a coup and Goryeo surrendered.
Regaining power from military officials with the support of the Mongols, the king decided to abolish Sambyeolcho in 1270. However Sambyeolcho, led by Bae Jungson, revolted against the government. They set up their own king and government on Jindo Island, located in the southwestern region. In 1271 the leader Bae asked Khubilai Khan to place his land under the direct rule of the Empire as other rebels did, but was refused. After several months Jindo fell to combined Goryeo and Mongol armies. At the end of the year the remnants led by Gim Tongjeong invaded Tamna Kingdom on Jeju Island and banished the Tamna king. In 1274 they were crushed by Goryeo and Mongols. As a result the Mongols directly controlled Tamna until 1294.
Today the Sambyeolcho insurgents are often praised as national heroes who made stubborn resistance to foreign invasions. In 1978 a monument to honor the Sambyeolcho Rebellion was built on Jeju. Other relics such as the Yongjang fortress on Jindo island are also maintained as tourist attractions  (http://cybertour.mokpo.go.kr/english_new/sub2_2_d.html).