Platform mounds were built along river as well as irrigation canal systems, suggesting these sites were administrative centers allocating water and coordinating canal labor. The Adena culture refers to what were probably a number of related Native American societies sharing a burial complex and ceremonial system.
The communities were located near good arable land, with dry farming common in the earlier years of this period.
According to the oral histories of many of the indigenous peoples of the Americas, they have been living on this continent since their genesis, described by a wide range of traditional creation stories. Other tribes have stories that recount migrations across long tracts of land and a great river, believed to be the Mississippi River.
The Hopewell tradition is the term for the common aspects of the Native American culture that flourished along rivers in the northeastern and midwestern United States from BCE to CE. They divided the archaeological record in the Americas into five phases;  see Archaeology of the Americas.
The Ancestral Puebloans possessed a complex network that stretched across the Colorado Plateau linking hundreds of communities and population centers. After World War II, an agreement was reached to divide Korea into two parts: a northern half to be controlled by the Soviet Union and a southern half to be controlled by the United States.
Recent reexaminations of Clovis materials using improved carbon-dating methods produced results of 11, and 10, radiocarbon years B. The Classical period of the culture saw the rise in architecture and ceramics.