Ancient warfare is war that was conducted from the beginning of recorded history to the end of the ancient period. The difference between prehistoric and ancient warfare is more organization oriented than technology oriented. The development of first city-states, and then empires, allowed warfare to change dramatically. Beginning in Mesopotamia, states produced sufficient agricultural surplus. This allowed full-time ruling elites and military commanders to emerge. While the bulk of military forces were still farmers, the society could portion off each year. Thus, organized armies developed for the first time. These new armies were able to help states grow in size and become increasingly centralized.