The continents of North and South America were "discovered" by the European civilizations in the late 15th century A.D., but people from Asia arrived in the Americas at least 15,000 years ago. By the 15th century, many American civilizations had come and gone long before but many were still vast and thriving. The best-known civilization in the Americas is perhaps the Aztec civilization, largely because they were at the height of their power and influence when the Spanish arrived. Warlike, intractable, and aggressive, the Aztecs conquered much of Central America. But the Aztecs are so much more than simply warlike.

Source: ThoughtCo