[kristloken]

However the real reason why Finns have had so little common with Finnic groups to the east is Russian historic isolation.

And allmost completely different ethnogenesis (any common factor was so long a go that they hardly matter anymore). Volga-Finnic lands were not only over run by Muscovites but were actually pretty much central for Turkic migrations (Huns, Bolgars, Kazars etc) and later Mongols. Turkic and Mongol peoples had no part in Finnish ethnogenesis, unlike Russians or Volga-Finnics.