Oh man, 15mm? Haha, they are so wonderful! Wow, exceptional.
As far as Mayans, look for internet sites about the murals of Bonampak. These original murals show you what Mayan warriors looked like. Who is going to face your Mayans? Aside from inter-city warfare, the great city states were basically already in great decline and abandoned by the time the Spaniards arrived. Subsequent "conquest" against the dispersed cities took a long, long time, 150+ years. The warriors they fought had little of the same regalia as depicted in the miniatures that are available.
Another area to game would be the "War of the Castes" or revolution that occurred in the Yucatan Peninsula between the mid 1800s to early 1900s.
Anyways, I ramble, thanks for your wonderfully painted masterpieces. I am in awe and... to be quite honest... jealous. Jealousy flows on this website, it's quite loaded with talent.