You don’t have to test bones to posit ethnic mixes in Chinese history. Just look at some of the Xian warrior statues. Some of them bore Western faces when I saw the early excavations in 1983 — Turks? Indians?
There was large presence of Sogdians(a branch of Persian race from Central Asia,) in Tang China. So were many other Caucasian or Turkish people from Central Asia or Northern Asia. Some of them rose high in military ranks.