In South America a lot of tribes were just absorbed without warfare, they joined together because it made financial sense. The Inca were well known for it.
There sure was a lot of ritual human sacrifice for being a peaceful peoples. Specifically child sacrifice in the case of the Incas. [1] And the Aztecs, boy oh boy lol
Mayans would go to war because they hadn't had one in a while according to my guide at Mayapan. At their peak Aztecs were sacrificing 80k+ people a year, usually war prisoners. This behavior is how the conquistadors were able to rally their enemies and topple them.