Henri Christophe
L'empereur
I like your idea!So for example a "Magrebi" civ could have 2 unique units, one of these come from their Tradition being this time the Numidian/Berber Zenata cavalry that could be used as mercenary/auxiliar by others civs
Maybe the same civ could have not junt one tradition, but more then one. As for example you gave of Marrocos, who is of a Magreb tradition could also be part of African tradition and Islamic tradition. And share with these tradition some unique units; on that way we get close of the ethnic units concept.
I was thinking about Elephant units, he can't just be part of African tradition, because was used just for Carthagen (as far I know). But was wide spread used in India and Indochina. Maybe we should have a tradition called elephant to englobe those nations and don't have innacurate unities.
And this tradition could subtrate units too, maybe should be more accurate if civs as the Aztecs don't have knights on it's tech tree. Maybe should be cool a tech tree for each civ based on theses traditions.