Re: Proto Indo European (Ringe 2009).

"As is usual with protolanguages of the distant past we can't say with
certainty where and when PIE was spoken; a reasonable guess will be
the river valleys of Ukraine in the centuries around 4000 B.C, though
one can't absolutely exclude a somewhat earlier date, and nor a place
somewhat further east. The best discussion of the "IE homeland
problem" is still Mallory 1989 (this is pathetic); it is cautious and
not fully conclusive, as is reasonable under the circumstance (Ringe
2009, p.2, parenthesis added).

Ringe, D. (2009). From proto indo European to proto Germanic: a
linguistic history of English volume I. Oxford University Press.
ISBN-13: 978-0199552290 (Paperback).

M. Kelkar

Let's say probably somewhere between Hungary and the Caspian. That's about where everyone narrows it down. Given that area is a plain, it allows for fluid movement and easy communication, especially among a group that seems to have either first discovered or first mastered the use of horses and wheels. And from there, over the Hindu Kush into India for most, but not all of the IA-speakers.