This interesting 2002 BBC Documentary explains the recent discovery in Peru of Caral, the oldest known South American civilization that predates the Mayan sites in central America by at least a thousand years.  It explains that there is no evidence of if being a war-like culture or them performing human sacrifices, but instead it was a prosperous trading hub where people brought fish to its inland location.

From the video page: “The magnificent ancient city of pyramids at Caral in Peru hit the headlines in 2001. The site is a thousand years older than the earliest known civilization in the Americas and, at 2,627 BC, is as old as the pyramids of Egypt.  Many now believe it is the fabled missing link of archaeology - a ‘mother city’.  If so, then these extraordinary findings could finally answer one of the great questions of archaeology: why did humans become civilized?”