I don't yet have the genomes from the recent Ning et al. paper on the Iron Age nomads from the Shirenzigou site in the eastern Tian Shan. But I do have most of the previously published data featured in the paper, including the Damgaard et al. 2018 Hun and Saka samples from the western Tian Shan.
After reading the Ning et al. paper between the lines and running a few analyses of my own, it's clear to me that most of the supposedly Tocharian-related Shirenzigou individuals actually share a very close relationship with the Tian Shan Huns, and indeed may have been their ancestors.
For instance, Ning et al. found that a large part of the ancestry of the Shirenzigou ancients could be modeled with the Tian Shan Huns, which was an anachronistic approach because the former are older than the latter. They also found that Ulchi-related ancestry was a key part of the genetic structure of eight out of the ten Shirenzigou individuals, and this likewise appears to be an important part of the genetic structure of the Tian Shan Huns.
Note the strong statistical fits in the Global25/nMonte and qpAdm mixture models below, respectively, which characterize these Huns as a two-way mixture between the Ulchi and the earlier Tian Shan Saka. And keep in mind that the Saka also harbor significant Ulchi-related ancestry.
Hun_Tian_Shan
Saka_Tian_Shan,92
Ulchi,8
distance%=1.2553
Hun_Tian_Shan
Saka_Tian_Shan 0.928±0.009
Ulchi 0.072±0.009
chisq 4.409
tail prob 0.992464
Full output
Moreover, the Shirenzigou males belong to Y-haplogroups Q1a and R1b (two instances of each), and they share the latter with one of the Tian Shan Huns. Judging by the data from the relevant BAM files, it's also possible that the Shirenzigou males share a very rare subclade of R1b with the Hun, defined by the PH155 mutation (see here). The Y-haplogroup assignments for the other Tian Shan Huns end at R and R1, but that's almost certainly due to missing data.
On the other hand, two Tian Shan Sakas belong to Y-haplogroup R1a but none to R1b, which fits with the pattern from currently available ancient DNA that R1a was more common than R1b in Saka-related groups, such as the Scythians and Sarmatians (see here).
This is all very interesting, because the Huns replaced the Saka in the western Tian Shan, and, considering their R1b and excess Ulchi-related ancestry, very likely moved into the region from the direction of Shirenzigou. Indeed, in my opinion a strong argument can now be made that the Iron Age population from the Shirenzigou region took part in the formation of the Hunnic confederacy.
So where does that leave the theory presented by Ning et al. that the Shirenzigou ancients may have been closely related, and perhaps even ancestral, to the Tocharians, simply because they packed a lot of Yamnaya-related and possibly proto-Tocharian Afanasievo ancestry, and were living close to the Tarim Basin, where Tocharian languages were subsequently first attested?
I'm not sure, but I now find it difficult to reconcile this theory with the fact that they were closely related, and probably ancestral, to the Tian Shan Huns. As far as I'm aware, Huns cannot be linked to Tocharians in any meaningful way.
Of course it's possible that different Afanasievo-derived groups were living in the Tarim Basin and surrounds, and, as some merged with new populations pushing into the region from the east and adopted non-Indo-European languages, others retained their Tocharian speech and eventually split into communities speaking Tocharian A, B and apparently also C (see here).
But this has to be demonstrated directly with ancient DNA from archeological sites where Tocharian languages were attested. Till then, I'll keep thinking that Ning et al. wrote a paper about Tocharians that really should've been a paper about Huns.
Here's a famous wall painting of Tocharian princes from the cave of the sixteen sword-bearers in the Tarim Basin, dated to 432–538 AD. They don't look like guys with a lot of Ulchi-related admixture to me, but I might be wrong. Feel free to let me know what you think in the comments below.
Update 08/17/2019: The Shirenzigou nomads are now in my dataset. Below are a few successful and not so successful qpAdm mixture models for them. Note that I tried to use a wide range of relevant "right pops", but also retain a lot of markers, specifically to be able to discriminate between different types of steppe and steppe-derived sources of gene flow (refer to the full output). Admittedly, the Shirenzigou nomads can be modeled with Afanasievo-related ancestry, but...
CHN_Shirenzigou_IA
KAZ_Botai 0.161±0.023
KAZ_Wusun 0.490±0.023
NPL_Mebrak_2125BP 0.349±0.019
chisq 5.793
tail prob 0.926172
Full output
CHN_Shirenzigou_IA
KAZ_Botai 0.143±0.022
NPL_Mebrak_2125BP 0.295±0.019
Saka_Tian_Shan 0.562±0.024
chisq 6.796
tail prob 0.870794
Full output
CHN_Shirenzigou_IA
KAZ_Botai 0.185±0.023
NPL_Mebrak_2125BP 0.428±0.021
RUS_Sintashta_MLBA 0.270±0.026
TJK_Sarazm_En 0.117±0.027
chisq 11.351
tail prob 0.414345
Full output
CHN_Shirenzigou_IA
KAZ_Botai 0.032±0.027
KAZ_Zevakinskiy_LBA 0.567±0.025
NPL_Mebrak_2125BP 0.401±0.019
chisq 15.157
tail prob 0.232961
Full output
CHN_Shirenzigou_IA
NPL_Mebrak_2125BP 0.452±0.031
RUS_Afanasievo 0.435±0.025
RUS_Okunevo_BA 0.114±0.049
chisq 19.808
tail prob 0.0708003
Full output
CHN_Shirenzigou_IA
NPL_Mebrak_2125BP 0.409±0.031
RUS_Okunevo_BA 0.173±0.050
Yamnaya_RUS_Caucasus 0.418±0.026
chisq 20.453
tail prob 0.0589872
Full output
CHN_Shirenzigou_IA
NPL_Mebrak_2125BP 0.464±0.033
RUS_Okunevo_BA 0.104±0.053
Yamnaya_RUS_Samara 0.432±0.027
chisq 27.189
tail prob 0.0072566
Full output
Both the Wusun and Saka are generally accepted to have been the speakers of Indo-Iranian languages. So it's possible that the Shirenzigou nomads were Indo-Iranian speakers too, or at least derived from such peoples.
Surprisingly, NPL_Mebrak_2125BP was the key to obtaining the best statistical fits. This is a trio of samples, roughly contemporaneous with the Shirenzigou nomads, from a burial site high up in the Himalayas in what is now Nepal (see here).
To be honest, I'm not quite sure why the Himalayan ancients work so well in my models. Perhaps they're just a really good proxy for an Iron Age population from the northern part of the Tibetan Plateau? By the way, most of the Shirenzigou nomads made it into the latest Global25 datasheets (see here).
See also...
Almost everything you ever wanted to know about the Xiaohe-Gumugou cemeteries
The mystery of the Sintashta people
Late PIE ground zero now obvious; location of PIE homeland still uncertain, but...