But I must!
I hope you dont end up using the photoshop there, sinse this is an excellent oppertunity to try some thing great.
It is very hard to put a border on any of the people you speak of.
At one time the Toltecs cross over, they were the first. They came to the Americas, and occupied an area in mexico. They were a cilvilized people, with a complex culture. In mexico they build a civilization, created art, cities, and then dissapeared. Awhile later a second group came into S.A, and occupied the same region, later moved on. Centuries later another group came to the \"third wave\" came, and occupied the very same region, but didnt manage the area to teh standard of the 2 people before them. Civilizations sprang up all over S.A with the following ages. Some speak of the Toltecs, and other groups manageing all the land, exchanging power and passing knowledge. It\'s not traces of the same art style we see developing through the ages in the land, but banks of knowledge pointing to a passing of culture amoung groups, from one to the next. Like a string!
Where you can draw the borders is a hard question to ask. Especially when groups have migrated around the map. I am not an expert on the subject.
If you are looking to a design, I would search out some \"Inca textiles\", which are truely a treasure, mystery, and an art form. Which can make for an excellent competition entry, no?
Heres a link to start. Have fun!

Design