It would seem that the Mongols, however, did not remain long in the south, for we read that when the standard of revolt was raised the following year at Na-ju, the Koryŭ forces, sent by the king, speedily overcame them. This would hardly have been likely had the Mongols been in force in that vicinity.
We must remember that the Mongols were continental people and knew nothing of the sea. Even the narrow strip of water between Kang-wha and the mainland daunted them. And so it was that the king from his island retreat defied the tremendous Mongol power.
By 1238, when the Mongols again flooded the country with their soldiery, the people had mostly found refuge among the mountains and on the thousands of islands which lie off the western coast of Korea. It would be impossible for anyone to imagine the suffering and distress entailed by these invasions. The records say that the people simply left their houses and fields and fled to these places of refuge. What did these hundreds of thousands of people live on as they fled, and after they reached their places of retreat? What breaking of old bonds of friendship and kinship, what rending of family ties and uprooting of ancient landmarks! It is a marvel that the land ever recovered from the shock. These Mongols were fiercer and more ruthless than the Japanese who overran the country three centuries later and they were far more numerous, besides. Plunder being their main motive, their marauding bands covered a much greater territory and mowed a much wider swath than did the soldiers of the great Hideyoshi, who kept to comparatively narrow lines of march. Nor did these Mongols meet the opposition which the Japanese met. The Mongols made a clean sweep of the country, and never again do we read of those splendid armies of 200,000 or 300,000 men which Koryŭ was once able to put into the field, even when groaning under the weight of a corrupt court and a rampant priesthood. It is from these days that dates that utter prostration of Koryŭ’s power which left her an easy prey to every Japanese freebooter who had 100 good swords at his back.
After ravaging to their hearts’ content the Mongols withdrew in 1236 to their own territory but sent a messenger ordering the king to go to Peking and bow before the Mongol emperor. He refused, but sent instead a relative by the name of Chŭn with a letter asking the emperor to excuse him from attempting the difficult journey to the Mongol court. Again the next year the same demand was made, but this time the king simply declined to go. The Mongols then modified their demand and ordered the King to come out from his island retreat and return to Song-do. This the king had no intention of doing; but the next year he sent another relation named Sun as a hostage to the Mongol court asserting that this was his son. The emperor believed this and married Sun to one of his own near relatives.