Ancient "Aryans" expanded from the Lake Baikal 20k BC to the rest of the world. The branch that stood in the steppe, domesticated horses, and expanded through whole asia. The branch that migrated north-east arrived to america and settled there till they got extinguished and assimilated everywhere except in some reducts (see chachapoyans).
The branch that migrated to south east asia stablished in Japan, their remains are that tribe who's name I don't remember, and the result is also in Japanese blood.
The branch that migrated into europe became the IE, splitting (before they even entred europe, while they were in the steppe, probably even in lake baikal) into the Nordics (or germanics) and Celts.
Ancient aryans were a super tribe that traveled throguh the whole world spreading their culture (cttle herding) and symbols (the swastika).
Tocharians invented budhism and spreaded it throguh asia.
Celts were hinuists and Budhists to some degree.
Tocharians are related to the IE that wrote the Vedas (they have their own texts).
Mongolian Empire was the peak of Asian civilization.