How to make friends with a group of people who don't wan to be represented and value ancestor worship.
Step 1: Represent their ancestors..
Anasazi, pueblo, or any derivation of them will not be in civ till our fellow fanatics have spread their claws into the hierarchies of their community. It's a shame, they'd be awesome.
Cahokia could be even better though, and I vote for them. The cree, Cherokee, Iroquois, etc are all empires past their peak anyway, having begun to suffer through chronic disease and population loss. They did not reach the kind of specialised organised society Cahokia had prior to European contact. Adding them over Cahokia is the height of Eurocentric hypocracy by placing increased value on a civ for having interacted with Europeans.