There are many early civilizations. Three of the early groups in the Americas, the Maya, Aztec, and Inca are very interesting to study. It is thought that these groups either came across a natural land bridge from Siberia or came across the coastal area of what is now the California coast. Both of these theories indicate the groups then moved to the south and settled.
The Maya were brilliant people. They had a mathematical and astronomy system and were very advanced in both fields. They were polytheistic and believed in sacrifices and rituals. There built one of the oldest and largest ball courts in the Americas. It is located at Chichen Itza. The village also had a sacrifice pool for the purpose of sacrificing young virgins. They did not have an empirical method of rule, but each area had their own ruler. Their pyramids were built to show the summer solstice on the steps and sacrifices were performed at the top of the pyramids on a stone slab. The sun on the steps looks like a snake descending the stone step pyramid. For an unknown reason, these denizens of the Yucatan area left their advanced villages and moved to the jungles. A small Maya group still exists today in Mexico and in the Yucatan. You can tour Chichen Itza, but you can no longer climb the mighty pyramid like you could in past times..
The Aztecs settled in the area that is now Mexico City. They were also polytheistic. They did have an empirical system with one ruler. Their capital city was surrounded by water and had an advanced canal and waterway system. There were only three causeways that allowed entry into the capital city. Just like the Maya they also believed in sacrifices that would take place atop pyramids. The Spaniards led by Cortes defeated the Aztecs. Mexico City is built on top of the ancient Aztec capital.
In the Andes Mountains and the valleys of the Andes, the Inca settled and lived. They too were believers of many gods and had one ruler. They were known for their superior bridges and well-developed road systems. The Spaniards also defeated them and Pizarro was the warrior who led the forces against them. The Spaniards wanted the gold and riches of the Inca. In addition to the Spaniards, disease also played a part in their demise. These three rich, smart, and advanced civilizations are interesting to study. Their mode of life and means of downfall are intriguing to explore.