Why is Kublai Khan's "Chinese law attached" limited?

Kublai Khan's "law attached to middle school" is based on the premise of not harming the vested interests of Mongolian aristocrats, so his innovation has great limitations. In order to persist in national oppression and prevent losing power, he consciously "attached himself to the Chinese law", but at the same time, he deliberately kept some old Mongolian systems, such as the food city system, the slave storage system, the official business system, the agency system, the hereditary system of military attache, and the establishment of the scholar Huachi (guarding officials). Mongolians, Semu people, Han people and southerners have a strict hierarchy in ethnic relations. In the 16th year of Zhiyuan (A.D. 1279), the Southern Song Dynasty perished, and after the reunification of China, the latent contradictions were gradually exposed. In the 19th year of Zhiyuan (A.D. 1282), Ahema, an official of Zhongshu Pingzhang who was good at politics, was killed. Ahema won Kublai Khan's favor and was also the most powerful in opposing Chinese law. Thousands of kings worked hard and hammered him to death. Kublai Khan tended to be passive and conservative in his later years, and the prince of Jin continued to implement the Chinese law and ended up dead.