But how come that all those various haplogroups and/or subgroups started to talk Proto-IE? When? Where?
Still the question remains: was pre-protoIE ethnic language of some tribe/subhaplogroup which managed to spread it around, or it was a lingua franca like let's say Swahili...
that is the big problem,
From arcaiology we can not hear what people spoke that time,
Even cultures with written speech we can not find what they are telling us, (example Mycenean Minoan Linear A and B, One can not be read yet)
so by Agriculture expand, or arsenic bronze expand, or horses and chariots, or iirigation, or Gold or Copper expand, even architectural simmilarities we are trying to guess where and when,
Also Exist the linguistic methods which to a very good point give good results but always solve part of problem,
Most academic show Eurasian steppe or minor Asia - North Middle East or South west Caucas,
yet Caucasian and Gedrosian component also in theories.
PS
Personally I am starting to think searching about Europe and Varna, but no gennetical yet,