Sorry to bump this but just wondering if you are still working on it?
Yeah.
Full game from 769 - 1444, Kamarupa -> Bengal -> India, with minimal intervention outside the subcontinent:
Political map mode
European cultures
African cultures
Asian cultures
Russian/steppe cultures
This was using all my mods, but only Multicultural World affects culture spread.
I don't believe any non-meltingpot or non-steppe culture has disappeared. The usual victims like Kurdish, Armenian and Georgian still exist. Castillian still exists in Iberia.
Bedouin has spread rather too much for my liking because for some reason it didn't break up. Khazar is very prolific because Khazar Muslims somehow inherited control of the Byzantine Empire, though I don't see that as a big problem since the real-life Turks were even more successful at assimilating the Byzantine Empire. Norse has spread rather prolifically as well.