Two roads, west or east

Earlier I was pondering the near-total wipeout of Central Europe and Balkan populations, courtesy the Slavs. Lately comes news from the east. How did they get to be (Russo-)Slavic?

The region is Volga-Oka, which means southeast of Moscow. Everyone here is R1a: specifically R1a-Z280 which gave rise to -CTS1211 and -Z92. So, still the old Russian taiga-steppe after the Indo-Iranians left for Andronovo and Sintashta.

CTS1211 is first caught in Lithuania, so presumably Baltic; 1900s BC. But it's all over the place now. Z92 seems rarer and stayed in the west. The demic spread long precedes the cultural shift to Russian. (This is a good illustration of how pots are language, not people.)

As to what they spoke before converting to Russian: it's hard to say. I don't think we have loanwords. More likely, they were already speaking a dialect more Slavic than Baltic. They pulled Old Russian toward them away from, oh, Jugoslavic.

We must now talk Uralic, with its male N signature. This is well known to have intruded into the west probably in the Iron Age. Some of this Volga-Oka territory is now Mordvin / Mordovian (yo, Quest for Glory IV!). The paper takes pains to separate Erzya from Moksha. But their ancestry is R1a too. Contrast the Finns and the late Hungarian nobility.

So I am guessing to the extent some of the Mords speak Uralic, they did this (independently) to interface with the Uralic fur-trade, and were not conquered. They probably spoke this paraSlavic beforehand. Maybe the Old Hungaria, now Khanty, had demic conquest but not the Mordvins.