Tocharians

  General Description   The period of Sogdian and Bactrian history between the disintegration of the Greco-Bactrian kingdom in the late 2nd century BCE and the rise of the Kushan Empire in the 1st century CE is poorly understood. The region was politically fragmented and the local settled populations were subjected to nomadic invasions, notably by a group of pastoralists and traders known to us by their Chinese name, Yuezhi. ^{[1] [2]} The Yuezhi are also sometimes referred to as ’Tochari’ by scholars who believe they spoke a Tocharian language, part of an extinct Indo-European language group. ^[1] (Others argue that their original language was eastern Iranic or proto-Turkic.) ^[3]
In the mid-1st millennium BCE and perhaps even earlier, the Yuezhi were living on the steppes to the north of China. ^[2] However, after coming into conflict with other nomadic groups, the Xiongnu and Wusun, they migrated towards Sogdiana. ^[1] By 129 BCE, when the Han Chinese diplomat Zhang Qian visited the Yuezhi court on the Oxus river, they were ruling over a region that included parts of the old Hellenistic Greco-Bactrian kingdom. ^[2]
In the early 1st century CE, the first Kushan king, Kujula Kadphises, seized power and began ruling over south-eastern Sogdiana, marking the end of our Yuezhi period. ^[4] Kujula Kadphises was probably a member of one of five Yuezhi factions or subtribes, which he succeeded in unifying through military conquest, ^[4] but even this is disputed.
Population and political organization
The Yuezhi in Bactria and Sogdiana seem to have been organized into a federation of five tribes that competed for political supremacy in the new territory. ^[5] There is no written or numismatic evidence of a centralized Yuezhi state with a single paramount ruler before the rise of Kujula Kadphises. ^[4] Historian Craig Benjamin has characterized Yuezhi control over the sedentary population of northern Bactria and Sogdia as that of a militarily superior ruling dynasty of nomads, ’pastoralist conquerors’ whose ’nominal sovereignty’ was acknowledged by the locals because they feared violence if they refused to submit. ^[1]
Secure estimates for the combined population of the ruling Yuezhi and the settled population under their control in this period are lacking.

[1]: (Benjamin 2006) Benjamin, Craig. 2006. "The Yuezhi Migration and Sogdia." In Ēran Ud Anērān: Studies Presented to Boris Ilich Marshak on the Occasion of His 70th Birthday, edited by Matteo Compareti, Paola Raffeta, and Gianroberto Scarcia, Electronic version. Transoxiana Webfestschrift Series I. http://www.transoxiana.org/Eran/Articles/benjamin.html. Seshat URL: https://www.zotero.org/groups/1051264/seshat_databank/items/itemKey/KEWTMPWX.

[2]: (Liu 2001, 264-65) Liu, Xinru. 2001. "Migration and Settlement of the Yuezhi-Kushan: Interaction and Interdependence of Nomadic and Sedentary Societies." Journal of World History 12 (2): 261-92. Seshat URL: https://www.zotero.org/groups/1051264/seshat_databank/items/itemKey/QZA3GBJ7.

[3]: (Hill 2009, 312) Hill, John E. 2009. Through the Jade Gate to Rome: A Study of the Silk Routes during the Later Han Dynasty, 1st to 2nd Centuries CE. An Annotated Translation of the Chronicle on the "Western Regions" from the Hou Hanshu. Charleston, SC: BookSurge Publishing. Seshat URL: https://www.zotero.org/groups/1051264/seshat_databank/items/itemKey/67NGJHIK.

[4]: (Hill 2009, 345) Hill, John E. 2009. Through the Jade Gate to Rome: A Study of the Silk Routes during the Later Han Dynasty, 1st to 2nd Centuries CE. An Annotated Translation of the Chronicle on the "Western Regions" from the Hou Hanshu. Charleston, SC: BookSurge Publishing. Seshat URL: https://www.zotero.org/groups/1051264/seshat_databank/items/itemKey/67NGJHIK.

[5]: (Liu 2001, 272) Liu, Xinru. 2001. "Migration and Settlement of the Yuezhi-Kushan: Interaction and Interdependence of Nomadic and Sedentary Societies." Journal of World History 12 (2): 261-92. Seshat URL: https://www.zotero.org/groups/1051264/seshat_databank/items/itemKey/QZA3GBJ7.