274 AFRICAN POLITICAL SYSTEMS
they are generally unsuited for constructive purposes other than building. This paucity of raw materials, together with a meagre food supply, contracts social ties, drawing the people of village or camp closer, in a moral sense, for they are in consequence highly interdependent and their pastoral, hunting, fishing, and, to a lesser degree, their agricultural activities are of necessity joint undertakings. This is especially evident in the dry season, when the cattle of many families are tethered in a common kraal and driven as a single herd to the grazing grounds.
Thus, while in a narrow sense the economic unit is the household, the larger local communities are, directly or indirectly, cooperative groups combining to maintain existence, and corporations owning natural resources and sharing in their exploitation. In the smaller local groups the co-operative functions are more direct and evident than in the larger ones, but the collective function of obtaining for themselves the necessities of life from the same resources is in some degree common to all local communities from the household to the tribe.
These local communities are the monogamous family attached to a single hut, the household occupying a single homestead, the hamlet, the village, the camp, the district, tribal sections of varying size, the tribe, the people, and the international community the limits of which are a Nuer's social horizon. We regard the family, the household, and the hamlet as domestic, rather than political, groups, and do not discuss them further in detail.
The distribution of these local communities is very largely determined by physical conditions, especially by the presence of ground which remains above flood-level in the rains, and of permanent water which survives the drought. In any village, the size of population and the arrangement of homesteads is determined by the nature of the site. When perched on an isolated knoll, homesteads are crowded together; when strung out along a ridge, they are more widely separated; and when spread over a broad stretch of higher ground, several hundred yards may intervene between one hamlet and the next. In any large village, the homesteads are grouped in clusters, or hamlets, the inmates of which are generally close kinsmen and their spouses. It is not possible to give more than a rough indication of the size of a village population, but it may be said to vary from 50 to several hundred souls. As explained, villages are separated by several miles of savannah.