Archaic Indians emerged during a warming trend that lasted from 7000 to 3000 BC and was marked by the radical change and diversification of stone tools. Folsom culture disappears, and is replaced by populations that are hunters and gatherers with technologies for processing grains, fruits, nuts, and gathered carbohydrates.
Population levels grew, and larger societal groupings emerged which included occupational specialization. Cultural diversity flourished and expanded exponentially, and Indians in the Central Valley of Mexico launched into a full-blown agricultural revolution. The emergence of trade networks marked this period, and hunting shifted from large game to medium and small game supplemented by plant foods. Large monumental structures including mounds and pyramids began to emerge in resource-rich areas like Meso-America and the Mississippi Valley. Artistic expression began to form in manufactured goods like pottery and basketry.
Human populations migrated into most of the territory that could sustain it, but once a “homeland” had been located, nomadic ranges declined in favor of semi-sedentary lifestyles supplemented by trade. As a result, culture groups began to differentiate themselves. Linguistic and cultural differences grew and spread as new “nations” began to be shaped by the region they came to inhabit. Anthropologists suggest that the population of North America happened during this period with the migration of a small groups of wanderers that displaced or absorbed the remnant peoples and then increased exponentially over some 9,000 years.