Before the development of aboriginal farming, America was occupied by marginal type tribes alike in simple technology and shamanism but with a complex history (10,000 yrs. or more) of diffusion and ecological adaptation producing great cultural diversity especially as tribes were forced into refuge enclaves in N. and W. and extreme S. The formative period developed agric. to support dense and stable communities, class-structured society, and priest-temple-idol cult as well as complex material culture from Mexico to Bolivia with diffusion effects in s.-w. North America and southern Andes. Circum-Caribbean equivalents stressed war complex and water transport. Andean high civilization developed practical (e.g., plant-breeding) and political potentialities of the formative period to where population grew so dense that war aimed only at conquest for tribute and the social and religious hierarchy was static. Maya civilization could survive on the basis of slash and burn farming with dispersed populations only with absence of war. Mexican civilization simply intensified formative period traits. Forest cultures of both N. and S. America borrowed the rain-forest technology of the Circum-Caribbean type, but not class system or cults. Traits diffused out through tropical forests and Eastern Woodland tribes were successively lost as they reached unsuited environments.