How to get more civs in a map

[MisterBarca]

Is there a way to get more civs into a given map? I cannot seem to be able to do it from the game set-up screen, though I can change the number of city-states. I think city-states are an interesting wrinkle, but it appears that the default civs v. city-states ratio is a bit off kilter.

 

[Keejus]

Advanced set-up -> Add AI player (lower left corner)