I have seen Khmer as Dai Viet with Siam also existing.
Suggestions:
1) Consider tweaking the culture spread for Inca on mountains, it seems like they have a normal culture spread rate for mountains which seems a little silly.
2) Consider increasing the Inca core size, due to goal #3 I was making a lot of cities and I got multiple territorial crises causing cities to secede due to small core size.
EDIT: I am wrong on #1, it appears that Inca does in fact get a bonus to culture spread on mountains, it treats them like hills, that said I don't know how the game calculates the cost for those tiles
Suggestions:
2) Consider increasing the Inca core size, due to goal #3 I was making a lot of cities and I got multiple territorial crises causing cities to secede due to small core size.
EDIT: I am wrong on #1, it appears that Inca does in fact get a bonus to culture spread on mountains, it treats them like hills, that said I don't know how the game calculates the cost for those tiles