:The CIA map suggested by  (https://www.cia.gov/library/publications/cia-maps-publications/maps/791363.jpg) looks reasonably accurate and includes the various areas I have mentioned in my previous comments. It might be reasonable to include the northern areas labelled "sparsely populated" in your geographical extent of Uyghur, as the western area is fully and the eastern area almost fully surrounded by Uyghur areas. The "sparsely populated areas to the south should not be added, as they are predominantly Tibetan (at least the southern part of it). I think the issue is now solved.