Not to discourage further comment, but you may be interested in several of the threads in our FAQ:

http://www.reddit.com/r/AskHistorians/wiki/nativeamerican

look under "Civilizations of the Americas"

Hope this is helpful!

I recommend reading a book called "Guns Germs and Steel" by Jared Diamond. He answers a lot of questions on why different countries developed quicker then others with his own theories that make sense.