Mongol Invasion of Tsushima and Jeju

The Mongol Invasion of Tsushima and Jeju took place on 1272, following the Mongol Invasion of Korea. Goryeo was fully subjugated by 1259, but Jeju - then known as Tamna - was still nominally independent. Meanwhile, Tsushima, while part of powerful Japan, was isolated and was a good staging point for the invasion.

In 1270, following the failed Sambyeolcho Rebellion, Tamna was overwhelmed by the rebel Kim Tong-jeong and his troops. The island was ignored until the end of 1271, when they began raiding the Korean coast. To counter this, in February 1272 a Mongol army of about 10,000 led by Kim Bang-gyeong crossed the Korea Strait and attacked Jeju, securing it in two months. The soldiers recovered for two months and crossed the strait again, this time led by Kim's subordinate Shingkhor Buqatai, to attack Tsushima. There was much more resistance this time, with reportedly 1,000 of the Mongol soldiers being killed, but the island was eventually overrun.

Jeju became a grazing ground for Mongol horses while Tsushima was used as the main base of operations, with Kaneda Castle being expanded to accommodate the increased administration. In 1274 and 1281, the Mongols attempted to invade Japan, but were defeated by typhoons and forced to retreat.

Following the massive defeat, Shingkhor Buqatai died ("of stress", according to Yuan records) and the Mongols formally left Tsushima; they would also leave Tamna in 1294. In practice though, Shingkhor Buqatai's son Sokhor Shinghkhor led the army and retained his presence in Tsushima, creating the Sokhor Empire.