The past couple of centuries have seen the Aztecs, an alliance of groups of whom the Mexica are the leading element, become dominant in Mesoamerica. South America is a continent located in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. It can also be considered as a subcontinent of the Americas,
It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean; North America and the Caribbean Sea lie to the northwest.
Most of the population lives near the continent’s western or eastern coasts while the interior and the far south are sparsely populated. The geography of western South America is dominated by the Andes mountains; in contrast, the eastern part contains both highland regions and large lowlands where rivers such as the Amazon, Orinoco, and Paraná flow. Most of the continent lies in the tropics.