Some General remarks about civilization in the Americas.

We can divide the Western hemisphere into three 
geographic areas where civilizations developed:  North 
America, Mesoamerica, Andean.  Each area did experience the 
growth of large cities and elaborate political and economic 
organizations, but when faced with European challenge they crumbled.
In addition, civilization in the Americas developed independently, which 
meant that there was no borrowing from other cultures (also no 
horses).

Mesoamerica proper would be Central America today.  The region saw a 
rise and fall of successive centers of civilization (Olmec, Zapotec, 
Maya, Toltec, Aztec), of which we know comparatively little--Christian missionaries
to the New World were extremely systematic in their destruction of native 
American texts, which were considered pagan, and also in their destruction of 
native Americans.  Within a century of Columbus' first voyage to the Americas, the 
native population had plunged by almost ninety percent.

We know most about the Maya, even though their glyph system of writing has 
only relatively recently been decoded.  They were extremely advanced in 
their mathematics and calendar systems, and their religious understanding
was extremely complex.  The popular forms of entertainment were the 
ball courts and ritual human sacrifice.

One thing that has always intrigued me was the ability of the Spanish and 
other explorers to communicate with the natives.  Given the fact that 
European languages and native Indian languages were quite dissimilar, it 
is amazing that within a few decades of 1492 communication barriers no longer 
existed.