Well, that's not too surprising.
Many common English words are practically Sanskrit.
(agni = fire <-> ignite)
Unfortunately
the question of the origin of the Indo-European languages has been politicized.
It is doubtful the answer ever will be known.
Personally, I believe the 'Aryan invasion' theory is nonsense.
However
the Harappan language
apparently has not been deciphered.
but it likely was not Indo-European
(as were not the original languages of South India).
The Indo-European languages probably spread out very slowly
over the course of thousands of years
as farmers migrated.
If I had to bet
I would say that the Indo-European languages had their origin
in the city of Çatalhöyük in the Anatolian plains of Turkey.
I once was astounded to see
in the Ankara museum of ancient history
a metallic heraldic ornament from this site
dating from 3000 BC
that was adorned with 19 Swastikas.
The Swastika
of course
is the symbol of the Indian religion
but also is found in other civilizations.
In a bas-relief on a mountain
at Ivriz, Turkey
(not far from Çatalhöyük)
there is a Hittite king
whose robe also is adorned with swastikas.
Most linguists that I've read agree that the Indo-European languages have their origin in ancient Anatolia.
Okay, now my take on it:
I believe the refugees from the Black Sea flood (Noah's Flood?) in 5,600BC spread the language and (in many cases) farming all across Europe and eventually some of these refugees made their way all the way to India-Pak and on into China (see red-headed mummies). Their mixed blood relatives, The Hakka, migrated all the way across China into Guangdong province of modern China. Some even believe these refugees are the Ainu of Japan but, I don't.