Explain the significance of the difference between central / south america and north america./4998138/6bf63a8d? utm_source=registration

While North America, Central and South America are all part of the western hemisphere, they historically have significant differences. In North America at least in what is now Canada and the US there were about 17 million indigenous people when the Europeans arrived. On the Great Plains and in northern what is now Canada they mostly had a nomadic existence, following the game like the buffalo. In what is now Mexico, and what is now Guatemala and Honduras, the Aztecs and Toltecs built large cities with temples and had sedentary well organized agricultural societies and relatively large populations. This was also the case with the Incas and their cities in the western part of South America.