Agriculture in the Third World has frequently been denounced as barbarous, primitive and wasteful in its use of resources. The world agricultural ‘system’ is a highly complex set of markets and of economic distribution and production systems, in which in the most developed economies almost all agricultural produce is distributed through centralized markets, whilst in the least developed economies most agricultural produce is consumed by the farmers themselves and their dependants. The non-tropical, or rather non-humid-tropical, area of the Third World is mostly arid and of less agricultural importance, comprising areas mainly of pastoral nomadism, floodplain and oasis cultivation, irrigation and dry farming. Irrigated farming is the most productive and the most distinctive form of farm practice in the arid lands, although irrigation is also widespread in wetter areas as a means of intensifying production. The Third World is heterogeneous in its social conditions and racial composition.