Could start as independents with a movable single capitol. Like a new category of independents. When they reach a unit threshhold become a crisis for non nomadic civs in their continent. With existing continental unit skins with a few additions. You could be Comanches, Turkish tribes, Huns, Bedouin, Golden horde, etc.
Playable with new and unique victory conditions. Other players ability to support their growth. With the option to settle down next age or not.
Playable with new and unique victory conditions. Other players ability to support their growth. With the option to settle down next age or not.