As in the title, how would one go about making the Tocharians survive as a distinct linguistic group for centuries after they died IOTL? If possible they don't just need to survive but also reach a position where they can reliably survive up to the modern day, kinda replacing new Uyghur.
Preferable earliest POD is 800 CE, you can push a couple centuries earlier but if possible attempt to use later PODs.
Edit: I know 800 CE is pretty late all things considered, still it's interesting to see if by changing the collapse of the Tibetan empire you can make them survive long enough.