1) “uighur” is a reconstructed identity promoted by intellectuals in the 20th century. there was a turkic uighur empire during the 8th century and later in the region of xinjiang, but it collapsed, and the most likely modern descendents of the 8th century uighurs are a small ethnic group (of the same name) currently resident around xian.

2) there is a difference in xinjiang between the northern half and the southern half. the north was traditionally inhabited by a mix of people, and until the 18th century had a dominant mongol presence. the manchus exterminated and expelled the mongols during this period and added xinjiang as part of their person domains. the majority of xinjiang’s population today is han chinese, but these are concentrated in the northern half of the province, around urumqi. along the ancient silk road route uighurs are still dominant; and in kashgar 90% of the population remains uighur.

3) by this, i mean that xinjiang was not initially assimilated into china proper. for most of its history it has not been part of the chinese empire (though during the height of the han and tang dynasties the oasis cities were). it was a personal domain of the manchus until the 19th century.

4) it is not correct that the uighurs have always been isolated. this century, after the community conquest, yes, but xinjiang is a chinese name (i think it means ‘new territories’). the cities of the silk road, kashgar, khota, etc., are simply the eastern terminus of the turkic world, and have long had connections cultural & political with the turkic polities of central asia, especially the ferghana valley.

5) so it should be no surprise that the uighur independence movement is based out of instanbul last i checked. the uighurs are “hooked in” to the turkic international; their language is intelligible with other turkic dialects after all.