Thanks for kind answer (too kind maybe?)
the ergative nature of Iranic languages was the reason for me they are the result of an acculturation of previously non I-Ean speakers by I-Eans come from elsewhere (so not from Iran surroundings), being the ergative aspect the heritage of a non-I-Ean substrata, at least in my modest mind. Maybe I'm wrong; could you confirm or infirm me the first I-Ean languages were ergative or not? It seems the syntacix proximity of I-E is rather with steppes (Finnic-Ugric) languages than with Caucasic ones...
aside, I recommend you to read the paper of Bryant and Patton to make your opinion
It has been said that there were 2 stages of PIE. The very first original evolved somewhere around the Zagros Mountains. That PIE migrated into the Maykop and from there it migrated into the Yamnaya. And in the Yamnaya it evolved into proto-Celtic, proto-Germanic etc.
Late PIE evolved in Yamnaya. It has been said that some IE languages spoken in Europe came from Yamnaya and not from Maykop or Iran (Leyla-Tepe). While some languages like Iranic evolved from the original PIE that stayed home on the Iranian Plateau.
There were 2 PIE stages.
Late PIE in Yamnaya and
early PIE on the Iranian Plateau. PIE in Yamnaya came from Maykop/Leyla-Tepe.
PIE that evolved in the Yamnaya Horizon was NOT ergative.
But proto-Iranic that evolved on the Iranian Plateau was an ergative language. The reason why proto-Iranic and proto-Indo-Iranian CAN'T be from the steppes is because some Iranic and Indic languages are still ergative languages. Native languages in the Steppes, like Turkic, Ugric, Mongolic, Russian (Slavic) etc. are NOT ergative languages at all and never have been, while proto-Iranic and proto-Indic were ergative languages. Ergativity in Iranic and Indic is from somewhere else. And that place has to be Iran, where ergativity is NATIVE to Caucasus & Iranian Plateau.
Proto-Iranian and proto-Indic can't be from the Steppes becasue there is no ergativity constructiuon in the Steppe. But there is ergativity construction in Caucasus and the Plateau.
Don't forget that BMAC was practically West Asian in nature, Indic languages are from BMAC. Those Aryans who invaded India came from North, from BMAC. So of course Indic has an ergativity.
There are many links between Caucasian and Indo-Iranian (proto-Iranic) languages. And even today Caucasian and Iranic languages share the same region, West Asia.
Caucasian languages and proto-Iranic languages could even share the ancient ancestry to some degree. both languages heavily influenced each other, that's for sure. They share even the same auDNA! Iran and Caucasus are linked to each other.
My last post with this name. This is against the rules. I'm banned. I'll come back in 2 weeks with my original name. Take care, ciao!