India was invaded by the Aryans of Central Asia, who likely had a lot in common with the Celtic people who went on to settle Europe.
"The Tocharians were the easternmost speakers of an Indo-European language in antiquity, inhabiting the Tarim basin in what is now Xinjiang Uyghur Autonomous Region, northwestern People's Republic of China. Their unique culture spanned from the 1st millennium BCE to the end of the 1st millennium CE. Their language is called Tocharian."
"The Knights With The Long Swords"
This is the Gansu Province of China and a handful of Caucasian only graveyards there were still being used into the 1300's. (The Chinese didn't show up in this region until about 200BC...they were the late-comers)
Posting such an idea can get you seriously flamed on some sites.
There is a whole group of Indians who for some obscure reason believe that saying the Aryans invaded India from Central Asia in the distant past is somehow insulting to India. They instead prefer a scenario where the Aryan languages originated in India and went west from there.
This is despite the fairly obvious fact that we have archaelogical and historical evidence of dozens of invasions of India from the northwest and exactly none going the other way.
I've never understood why they react this way, as the most common theories have the Italics, Greeks, Celts and other Indo-Europeans originating outside (western) Europe just as much as they do outside India.