In the Mongol empire a number of peoples and cultures met and were mixed together, and its rulers did not force people to follow the Mongol customs. Mongols had their own law called jasagh, but, except for a few articles, they did not try to apply its entire regulations to the people under their rule. In fact, it was improbable from the first to formulate a single legal code that could embrace various ethnic groups in the empire all of which had their own distinctive legal customs. Therefore, they applied jasagh to the Mongols, shariah to the Muslims, and Chinese law to the Chinese, i.e, both Hanren and Nanren, There is no doubt that the so-called Yuan law codes, such as Zhiyuan xinge, Dayuan tongzhi and Zhizheng tiaoge, and privately compiled Yuandianzhang too, were basically made to govern the Chinese. In these codes we find some cases dealing with Mongols and Semurens, but they are the cases involving more than two different ethnic groups. Viewed from this perspective, the case of Koryo people was rather peculiar. First of all, Koryo people living in the realm of Yuan empire, including those in Liaodong area, were classified as a group similar to Hanren and Nanren and received legal treatment accordingly. Although in the beginning there seems to have been some confusion about this classification in view of a few cases where Koryo people were treated not different from Semuren, in the end they were excluded from the category of Semuren on the basis of the judgment that Koryo people had family names just like Hanren. However, the Koryo people living in the peninsular, unlike those in the Yuan territory, were not the subject to the Yuan law. The articles about Koryo people found in the extant Yuan legal codes are for those who were living in the Yuan domain. In other words, because Koryo was acknowledged as an independent political sphere directly under the rule of the king of Koryo, the people under his rule were also considered to be out of the confines of law that regulated Hanren and Nsnren. In this respect, a series of incidents that took place around 1340 were diametrically contradictory to the legal practice current at that time. The prohibition against carrying weapons, imprisonment of King Chunghye after the death of King Chungmok, and political maneuvers of the Simwang group were all denying the political and legal autonomy of Koryo. It is not surprising to see that officials and intellectuals of Koryo were shocked at this unexpected development and realized the gravity of the situation. Therefore, the "Proposal for Semuren" that was raised in this strained milieu and put forward to break through such critical situation should not be regarded as an argument only to improve the status of Koryo people. Rather, it was brought up to declare the true identity of Koryo people and to make the Yuan court acknowledge it. The logic behind the "Proposal" was that Koryo made contributions twice, by "giving assistance with troops" in the time of Chinggis Khan and and by "submitting spontaneously" in the time of Qubilai, Because of these contributions Koryo king could become 'the son-in-law' of the emperor and his kingdom was guaranteed "not to change local customs". Thus, according to Lee Jehyon and An Chuk who wrote the "Proposal", Koryo people should be distinguished from Chinese and classified in the same category with Semuren.