Runion, Meredith L. The history of Afghanistan. Westport, Greenwood Press, 2007. ISBN 978-0-313-33798-7. с. 46. The Yuezhi people conquered Bactria in the second century B.C.E. and divided the country into five chiefdoms, one of which would become the Kushan Empire. Recognizing the importance of unification, these five tribes combined under the one dominate Kushan tribe, and the primary rulers descended from the Yuezhi.
