In the Middle Ages (about 476 ~ 1453), from the end of the Song Dynasty to the middle of the Ming Dynasty in China, the Xiongnu was defeated by the Han Empire and split in two. Xiongnu in the east moved to Europe and became mercenaries at that time. Rome in the west was destroyed by Xiongnu, but the Han Dynasty was not medieval Europe. In the Song Dynasty, the Mongolian army once moved to the European continent and reached the Netherlands as far as possible. The Mongols established a vassal state led by Mongolian nobles in some parts of Europe, which was essentially similar to a colony. According to statistics, more than 60% of Europeans are descendants of Mongols, which is enough to prove that many Mongols moved to Europe at that time. In addition, every dynasty, every generation has a fleet of merchants going to Europe and a small number of settlers. From 15 to 18 century, probably from the middle of Ming Dynasty to the middle and late of Qing Dynasty, there were no large-scale immigrants like Xiongnu in Han Dynasty and Mongolia in Yuan Dynasty.