Starting Factions in BI

[RTW King]

Does anyone know how many factions are there at the start of a campaign in BI? I'm not sure, I think just 5 factions appear later on (Romano-British, 2 Roman Rebels, Ostrogoths, Slavs). I need to know for a mod I'm working on.

BTW, how hard is it to change whether a faction is there at the beginning of a campaign or not, and how do you edit the conditions which make them appear if they arrive later on?

[Antagonist]

As to your first question, I count 15 factions (16 if you include the Rebels) You enumerated the remainder yourself.

Antagonist