What role did nomads play in Chinese history?

Nomads inhabited the territories north of the historical Chinese lands, that is, modern Mongolia, Uyguria, Inner Mongolia, Manchuria. They often attacked and plundered China. That is why in the III century BC. to defend against them (the Xiongnu) they built the Great Wall of China.

In the XIII century, the nomads Mongols conquered China (1215-1279) and created the Yuan Empire on its territory, it existed until 1368. During this period, China visited Marco Polo and the Yuan troops invaded Japan and Burma (destroyed the kingdom of Bagan there).

In the middle of the 17th century, the Manchu nomads conquered China again and founded the Qing empire.