The Tocharians were the easternmost speakers of an Indo-European language in antiquity, inhabiting the Tarim basin in what is now Xinjiang Uyghur Autonomous Region, northwestern People's Republic of China. Their unique culture spanned from the 1st millennium BCE to the end of the 1st millennium CE. Their language is called Tocharian.
The Tarim mummies suggest that precursors of these easternmost speakers of an Indo-European language may have lived in the region of the Tarim Basin from around 1800 BCE until finally they were assimilated by Uyghur Turks in the 9th century CE.
"It has been suggested that this group may have been a relatively small group of Afanasevo/Tocharian refugees fleeing to the south, away from Indo-Iranian expansion arriving from regions west and southwest of the Sayan-Altai"