In the 2nd century BC, many Sakas were driven by the Yuezhi from the steppe into Sogdia and Bactria and then to the northwest of the Indian subcontinent, where they were known as the Indo-Scythians. Other Sakas invaded the Parthian Empire, eventually settling in Sistan, while others may have migrated to the Dian Kingdom in Yunnan, China. In the Tarim Basin and Taklamakan Desert region of Northwest China, they settled in Khotan, Yarkand, Kashgar and other places, which were at various times vassals to greater powers, such as Han China and Tang China.