Among the 56 ethnic groups in China, which ethnic group immigrated to China from other countries and became the China ethnic group?

According to historical research, among the 56 ethnic groups, there are Hui, Russian and Korean who immigrated to China from abroad, and they do not belong to the traditional ethnic groups in China. There are some transnational nationalities in the northwest, north and southwest, but it can also be verified that they lived in China for a long time in ancient times, while Russians mainly immigrated to China in order to escape the war and the panic of the Soviet Union during the Republic of China! They are mainly defeated soldiers, nobles, ordinary people, capital businessmen and so on in old Russia; The Korean nation was dominated by the late Qing Dynasty and the Republic of China, which was related to the domestic situation in North Korea. China was defeated in the Sino-Japanese War of 1894-1895, Japan occupied Korea, and people who didn't want to be conquered poured into China. As for the Hui people, they immigrated to China in the Yuan Dynasty. At that time, with the rise of Temujin, with the efforts of his son and grandson, Mongolia first conquered the northwest of China, then Central Asia, and finally most of the Middle East and Europe were their territory, which was also the peak of the ancient cavalry. The key is that there are few people, so some conquered Middle Easterners and Central Asians form logistics support teams to help them fight. Finally, in order to defeat the Southern Song Dynasty in one fell swoop, these Muslims were sent to China, initially forming the Hui group in the Ming Dynasty. It can be said that the Yuan Dynasty was the strongest, and it only represented the highlight moment of ancient cold weapons and cavalry. Except for a short period of time, he didn't have any strength and strong cultural civilization, and he would eventually decline. His territory was finally given to others and was annexed by Muslims, which brought great security and civilization hidden dangers to China in the later period. This has also led to Muslims in Xinjiang, China. It's like some serious diseases. I wonder how long it will take to cure. Therefore, the Mongolian Yuan Dynasty really did not bring any contribution to China, but brought serious diseases.