From what I can tell, the eventual list is: Aztec, Chimu, Inca, Mapuche, Chancas, Diaguato and Maya.
Other good [or at least potential] factions to include IMO: Tarascans (a/k/a Purepecha), Muisca, Cañari, Nicarao, Guaraní, Chachapoyas, Taíno, Tairona, Mixtec, Zapotec, and either the Qolla or Lupaqa (both were Aymara kingdoms around Lake Titicaca).
Also, what's the time frame for the mod?
