Most Native American groups could not form large Empires
like the Aztec and the Inca did because they were spread out in large regions
or territories. This did not allow them to form closed groups and create a
large Empire. Also the native groups were of the opinion that the lands could
support only a few people and so they never tries to attach with other native
groups to create a large enough Empire. Most people lived their life on
irrigation and so they did not want more competition from other tribes
regarding the land they had.