They would have been speaking the same language, BTW.
The Romans smartly brought folks in from Ossitia who spoke the same language.
The Scythians, or proto-Scythians you are referring to are probably the linguistic fellows of the folks who ran Troy, or Illium, or, in their own language, Allium!
Recall that big find at Ebla? Most eyes were on the mention of David and Soloman. My eyes were on the letters from the King of Troy! They were in a written Celtic language. The Greek tradition was that in that time the Celts were totally illiterate (which is still the English tradition).
With Troy at one end of the Silk Road, it's not hard to imagine that the folks around Troy as well as the hard working traders on the Road all the way to China all wore kilts.
Something happened in that period to cause the Picts, Scota and others to flee to the far West.
Thanks for the reply. I knew you would add something interesting.
I think it was a massive drought.
The Hakka (Chinese), who I think are the Asian equivalent of the (European) Picts, migrated all the way from the Tarim Basin region to Southern China. To this day, they are known as 'the guests' in China.
I think the people from that region were of mixed Caucasian/Chinese race and the mainly Chinese mix (Hakka) fled into China and the mainly Caucasian mix (Picts) fled west.
The Hans later conquered the whole region to the Caspain Sea and even made contact with the early Roman empire.