The presumption, under the Carneiro Hypothesis, is that agricultural intensification, and the social coordination and coercion necessary to achieve this end was a result of warfare in which vanquished populations could not disperse; the coercive coordination necessary for increased production of surplus is, under Carneiro's hypothesis, a causal factor in the origins of the State. For example, the mountainous river valleys of Peru which descend to the Pacific coast were severely environmentally circumscribed. Amazonian populations could always disperse and maintain sparse contact with other, potentially hostile, neighbors, whereas Andean coastal populations could not.