 Various nomadic tribes, such as the Yuezhi, Saka, and Wusun are conjectured to be part of the migration of Indo-European speakers who were settled in Central Asia at that time.The Ordos culture (6th to 2nd centuries BCE) in northern China east of the Yuezhi, whose excavated skeletal remains have been predominantly Mongoloid.The first reference to the nomadic Yuezhi was in 645 BC by Guan Zhong in his Guanzi (Guanzi Essays