According to Dr. Victor Mair, the populations did not belong to a single genetic or linguistic stock, nor did they come from a single source. They entered the Tarim Basin at different times and arrived from different directions. It is known that they rode horses, used chariots and had at least some medical knowledge. One of the Tarim mummies was found with evidence of a surgical wound on its neck, which had been sutured.
The extreme aridity and saline soils naturally mummified the bodies. Severely cold winters also played a significant role.
In 2009, the remains of individuals found at a site in Xiaohe were analyzed for Y-DNA and mtDNA markers. They suggest that an admixed population of both west and east origin lived in the Tarim basin since the early Bronze Age. Dr Mair claims that “the earliest mummies in the Tarim Basin were exclusively Caucasoid...” with east Asian migrants arriving in the eastern portions of the Tarim Basin around 3,000 years ago while the Uyghur peoples arrived around the year 842.
Wade, Nicholas (2010-03-15)."A Host of Mummies, a Forest Secrets". The New York Times. Retrieved 2017-01-29. 
Schmidt, R. (n.d.). The Mummies of Tarim Basin - Xinjiang Province of China. Retrieved March 07, 2017, from http://www.thelivingmoon.com/43ancients/02files/The_Mummies_of_Tarim_Basin.html
Wong, E. (2008, November 18). The Dead Tell a Tale China Doesn’t Care to Listen To. Retrieved March 07, 2017, from http://www.nytimes.com/2008/11/19/world/asia/19mummy.html