Nomadic group from Chinese Turkistan which moved west across Iran and south into the Indus region in the late 2nd century BC. They ruled in Bactria and India from about 128 BC-450 BC. About 128 BC the Yüeh-chih were recorded living north of the Oxus River (Amu Darya), ruling Bactria as a dependency, but a little later the Great Yüeh-chih kingdom was in Bactria, and Sogdiana was occupied by the Ta-yuan (Tocharians). They gave rise to the Kushan kingdom of the early 1st millennium AD in northern India and Afghanistan.