I have been playing as the Aztecs in the Custom Campaign Mod (someone please fix it so you can hire agents or build mines.) and although I haven't invaded anywhere against a faction yet (reason in next post) it is so easy to build all of your units. You don't need to build a barracks for this or an archery range for that, you get EVERYTHING from upgrading the walls except the Coyote Priest.

So, after I finish my experiment this time I will try to blitz the hell out of the world and burn everything to the ground. The Aztecs are the Slash and Burn Blitzers dream come true.