I agree with Madmanofaleader, you should have use something else besides aztec units. From what I know & the pics I have seen, the indigenous people weren't that fully dressed like the aztecs were made by Bakuel.
Maybe you should use berni14's tribal units.
Here's the problem with all this in South America, right now you have the Aztec's (already great units made), Inca (units made), Maya (units made), Toltec (units made), Mapuche (units made), and in the new mod i am making a combination of all in the civ South America itself.
Now that Bakuel made these other great Aztec units, had to place them some place.

Plus there are Chile and Argentina left.
Just image doing this for the Country to the North, America, i dont think you'd come up with 48 different civs without overlapping alot of them.
But i am always up for anything anyone has better than me, just tell me where to look and where to put them and maybe i will do it, never know.

Ideas are ALWAYS welcome!!
EDIT: WOuld really like to hear from someone from South America, your ideas, options??