Analysis of information sources in references of the Wikipedia article "Kuşan İmparatorluğu" in Turkish language version.
The Yuezhi people conquered Bactria in the second century BCE. 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.
At the end of the 3rd century, there began in Chinese Turkistan a long migration of the Yuezhi, an Iranian people who invaded Bactria about 130 bc, putting an end to the Greco-Bactrian kingdom there. (In the 1st century bc they created the Kushān dynasty, whose rule extended from Afghanistan to the Ganges River and from Russian Turkistan to the estuary of the Indus.)
