If there is no environmental circumscription, then losers in a war can migrate out from the region and settle somewhere else. If there is environmental circumscription, then losers in warfare are forced to submit to their conquerors, because migration is not an option and the populations of the conquered and conqueror are united. The new state organization strives to alleviate the population pressure by increasing the productive capacity of agricultural land through, for instance, more intensive cultivation using irrigation.