Hello:

I know some fractions belong to the same culture group. There is no cultural penalty when occupying a settlement that belongs to the same culture. For example:

Group 1: Romans (Senate, Julii, Brutii & Scipii)
Group 2: Greeks (The Greek citieis, Macedon)

I wonder are there any other groups that are compatible with each other? If you know any please list below. Thank you very much.