Nomad horsemen who began harrying northern Chinese states c.300 bc. Their homelands were in southern Siberia and Mongolia. It was to fend off their incursions that some Chinese states built walls, later joined together to form the Great Wall of China. The most serious attacks came under the early Han, after the Xiongnu had formed a league under their Shan Yu (Heavenly Ruler). In the confusion following the Han’s collapse, claiming descent from Chinese princesses, they set up ephemeral dynasties in northern China. Thereafter Chinese records make no reference to them. The Eastern Turks, who submitted to the Tang emperor Taizong, are thought to be their descendants.