The dissolution into tribal organization was not a descent into anarchy. The tribes, or kinship groups, already had a strong and effective structure. They probably also already had some understanding about which territories were their logical dominions; but here they cooperated sufficiently to establish clear boundaries. It was certainly in their best interests to decrease the threat of warfare, which would drain away resources and hamper their main task of growing food for their people. Each community needed to be able to supply its own needs. It could do that best under peaceful conditions.