The Yuan Dynasty maintained a rather special relationship with Goryeo. Since the reign of Yuan Shizu Kublai, almost every king of Goryeo was a son-in-law of the Yuan emperor (although his queen may not necessarily be the biological daughter of the Yuan emperor). The beauties of Goryeo also became a special tribute. After the fall of the Yuan Dynasty, the Ming Dynasty continued to receive such tributes, and later the Qing Dynasty was no exception. Granting Goryeo women as concubines to ministers also became a form of imperial favor. However, the formation of this relationship did not happen overnight but gradually formed after a protracted war.
At that time, the Kingdom of Goryeo was located on the Korean Peninsula, not far from the northern desert where the Mongols rose. Therefore, soon after the rise of the Mongols, they established contact with Goryeo. In 1216, a group of Khitan troops originally affiliated with the Mongols failed in their rebellion and fled into Goryeo, occupying the eastern city of Goryeo. They used it as a base for looting and destruction. In 1218, the Mongol general Hachun led a large army to pursue the Khitan rebels into Goryeo. The Goryeo king sent General Cho Chung to assist with troops and provided supplies to the Mongol army. The next year, the defenders of the eastern city surrendered, and Hachun and Cho Chung held an oath-taking ceremony, agreeing that Mongolia and Goryeo would be brotherly nations. However, the Mongols were obviously not very polite to this "brotherly" nation. From then on, they sent envoys every year to demand various items from Goryeo (from furs and silk to writing brushes, ink, paper, and inkstones), making the Goryeo people feel that "the Mongols are the most ferocious among the barbarians." The Mongols' annual extortion of huge sums made Goryeo unable to catch its breath, and the sentiment against the Mongols gradually intensified. In 1225, a Mongolian envoy was killed on his way back from Goryeo. Although the murderer was never found, the Mongols still blamed Goryeo. In the eyes of the Mongols, killing an envoy was an unforgivable sin, and they had gone to war with other countries multiple times for this reason. But because the Mongol army was campaigning westward, followed by Genghis Khan's death while fighting the Western Xia, the Mongols did not immediately retaliate against Goryeo. It wasn't until 1231 that the Mongol army first attacked Goryeo, and the victorious Mongol army pushed straight towards the Goryeo royal city. Helpless, King Gojong of Goryeo sent envoys to negotiate peace. After extorting a huge amount of wealth, the Mongol army retreated. However, they left 72 darughachi (governors) in various capitals, prefectures, and counties of Goryeo to indirectly control the country.
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