It's pretty clear that the Chinese found a non-Iranian (non-Aryan) skeleton. At the same time the Chinese also find Iranians as far East as Western China in the earliest times.
The period under study is at the time of the Qin emperor (who is the first emperor of what we can call "China"). That's a long time ago.
In later periods, e.g. Ming, it was common for Iranian-type folks to become high government officials in China.
Celts lived along the Black Sea and the major rivers feeding into it.
Is it corrrect to call anyone with red-hair a Celt or a proto-Celt?