There was some question regarding possible Scythian admixture into the early Zhou below. This is possible because of the Zhou dynasty, arguably the foundational one of Chinese imperial culture (the Shang would have been alien to Han dynasty Chinese, but the Zhou far less so), may have had interactions with Indo-European peoples to their north and west. This has historical precedent as the Tang dynasty emerged from the same milieu 1,500 years later, albeit the Tang were descended from a Turkic tribe, not Indo-Europeans.
I looked at some of my samples and divided the Han into a northern and southern cluster based on their position on a cline (removing the majority in between). I also added Lithuanians, Sardinians, Uyghurs, Mongols, and Yakut. As you can see on the PCA the Mongols are two clusters, so I divided them between Mongol and Mongol2.
Running ADMIXTURE after some outlier removal you see that the northern Han are distinct because they share ancestry from the Yakut modal cluster. In contrast, the Mongols and Uyghurs have ancestry from the Lithuanian modal cluster. Uygurs also have quite a bit of ancestry from the Druze modal cluster, which is West Asian. Also notice that the Mongol2 cluster, which shares more ancestry with the Yakuts also has more Lithuanian modal cluster ancestry. Two of the Mongol2 individuals are labeled as Khalkha.
Using some of the Sarmatian/Scythian samples from David Reich’s lab, I ran ADMIXTURE again. These ancient samples need to be interpreted with caution, as usual. But notice again that the northern Han obtain their minor ancestry from the Yakut. The Iron Age nomadic modal ancestry is found at low levels in the Mongols and Uygurs. I think this is a real effect. The presence of Alans with the hordes of the Mongol Empire is well attested, though the admixture is almost certainly earlier.
I ran some three population tests. This is what was notable.
- Han_N looks like it is mixed somewhat with Yakut
- Mongol has gene flow from Mongol2
- Mongol2 has gene flow from Lithuanians and Iron Age nomads
I literally spend an hour on this assembling the data. But I think the easiest conclusion to draw is that the “West Eurasian” shift in modern Chinese (north) is probably mediated through Turkic people.