Nomadism is found mostly in marginal areas which support only relatively sparse populations, particularly in the arid and semi-arid regions of Africa and Asia. It is a traditional form of society that allows the mobility and flexibility necessary for relatively even use of vegetation over large areas of low quality rangeland. It also facilitates more social interaction than would be possible among people living in small scattered settlements. Since nomads cope successfully with both social and ecological problems in areas where other people don't want to live, their way of life deserves careful attention. Nomadism involves ways of thinking about space and people which may be important for successful economic development in marginal areas.