TBH I wouldn't expect Xinjiang mummies to be of Indo-European origin, given that Xinjiang is in east Asia. What's the background here?
Well, it's in Asia. It's very much a part of the steppes that run into Europe, better connected to them than it is to, say, China. There isn't really a natural geographic division between "Europe" and "Asia".
There was another Indo-European culture present near there several centuries later: https://en.wikipedia.org/wiki/Dayuan
Worth noting also that India is much more difficult to get to from Ukraine than Xinjiang is, but they have a very strong Indo-European presence - that's why it's called "Indo-European" and not just "European" or perhaps "Perso-European".
Speaking of which, connections between China and Persia have always been extensive. The Tocharians are not Iranian, but it would hardly be a surprise if Iranian-speaking groups had ended up in their place.
Could you elaborate? I was intriguged so I measured on google maps. Ukraine to Xinjiang is around 2500 miles. Ukraine to India is around 2400 miles. "strong Indo-European presence"? I would imagine it is easier to go south along the coasts to India than it is to cross the deserts to Xinjiang.
Hindi is an Indo-European language. As I mentioned above, that is the reason for the term "Indo-European" in the first place.
India is not entirely Indo-European speaking; about 20% of the population speaks a Dravidian language instead. But I feel comfortable describing almost 80% of the population as being "a very strong Indo-European presence".
> > India is much more difficult to get to from Ukraine than Xinjiang is, but they have a very strong Indo-European presence
> Could you elaborate? I was intrigued so I measured on google maps.
Straight-line distance is not informative as to how easy it is for a human to make the journey. Proto-Indo-Europeans used a cultural toolkit involving horse-drawn chariots. They started out in the steppes north of the Black Sea, which I've referred to above as "Ukraine". But look at this map of the steppe: https://en.wikipedia.org/wiki/Eurasian_Steppe
You can get to Xinjiang from Ukraine by riding a horse east through the steppe. (Admittedly, and then detouring a bit south into a desert. And riding the horse may be anachronistic.) You're spending almost the entire trip in the same climate and terrain you're already familiar with.
But going to India involves leaving the steppe to cross some rather different terrain, after which you end up in the tropics.
In fact we know the Aryans did get bogged down on the way to India; we have records of Indo-Aryan speakers ruling a kingdom in the north of Mesopotamia at a time when they hadn't yet reached India: https://en.wikipedia.org/wiki/Mitanni . These people did not blaze a path of conquest all the way to India; the territory around them was held by Semitic speakers and has been continuously from then to now.
Wikipedia has a decent gif of the spread of Indo-Europeans over time: https://en.wikipedia.org/wiki/File:Indo-European_migrations....
Note how they start in Ukraine and it's easier for them to move a couple thousand miles east along the steppe (Afanasievo) than it is to move 50 miles north (Corded Ware).
It is possible that these were those who brought the Tocharian languages in the region.
The Tarim mummies from South Xinjiang did not look like the current population of this region and they had various resemblances, e.g. in clothes, with some Indo-European populations, so some believed that they might have been the ancestors of the later Tocharians.
The study has shown that they did not have genetic links either with their Indo-European neighbors or with the modern population.
Nonetheless, this does not contradict the fact that the old Tarim inhabitants seem to have been influenced culturally by the Indo-Europeans, who at that time were close to them (e.g. in pastoral & clothing techniques).
There was an IE culture in Xinjiang, the Tocharians.
A few thousand years ago, places like Xinjiang and the Iberian peninsula or Scotland were both on the outer edges of Indo-European expansion.
History had it that the Tocharians in Xinjiang were since then assimilated by non-IE people, while the pre-IE population in western parts of Europe was assimilated by IE people. (With the exception of the Basques.) But Xinjiang speaking an IE language was, at its time, about as normal as future England doing so.
Apart from the other comment pointing to the Tocharians of Tarim Basin who were Indo-Europeans, the only thing the classification Indo-European means that the language they spoke had Proto-Indo-European as a common ancestor. Even right now there's an Indo-European language right across Xinjiang's border - Tajik. This wouldn't have been anything out of the ordinary.
"Please use the original title, unless it is misleading or linkbait; don't editorialize."
The Eurasian steppe goes practically uninterrupted from Hungary to Manchuria, and it's a great big horse highway.