Nomadic pastoralism represents one of the great advances in the evolution of human civilization. Originating about 9,000 years ago, with the domestication of sheep and goats in what is now northern Iran, it is a specialized type of agricultural production in rangeland areas where extensive animal husbandry is more supportive of human culture than cultivated crops. People who specialize in raising livestock requiring frequent movements are known as nomadic pastoralists, or nomads.