A tribe is a regional security organization. It ties together a number of local primary face-to-face groups. It is charged with control of territory, defense against outside intruders, and protection of humans, livestock, and productive resources, such as wells and cultivation. Whatever productive activity tribesmen are primarily engaged in, such as pastoralism or cultivation, each male, with the exception of holy men, serves also as a warrior.
Tribes are usually defined by a symbolic idiom that asserts a primordial connection among tribesmen. Descent from a common ancestor is an idiom used to define many tribes. Tribal names are often those of the ancestor that all members share. Internal divisions may also be defined by ancestry; a descent idiom allows group divisions at every level of the genealogy.
Tribal subgroups are also charged with security and are defined as having “collective responsibility”; that is, the moral norm is that each member is responsible for what other members do and, as a consequence, all members are seen by outsiders as equivalent. There is also a moral norm to aid fellow tribesmen, the obligation stronger for close kin, weaker for more distant kin. Internal tribal relations among subgroups are based on what anthropologists call “balanced opposition” or “complementary opposition.” Each tribal subgroup is “balanced” against other subgroups of the same genealogical order, which in principle, and often in practice, serves as a deterrent against hostile acts.
Tribal leadership can take the form of primus inter pares. However, in tribes in contact with states, more formal leadership roles, with at least the trappings of authority and power, can develop. Whatever the role of the tribal leader, he depends upon consent of the tribesmen. In tribal subgroups, political process tends to be highly democratic, and leaders are those who can elicit agreement among the members and then carry out the will of the community.
Tribes are social organizations that are not static and do not always maintain form. They respond to environmental opportunities and constraints. If a state nearby is in trouble, with failing leadership and an unruly population, a tribe may mount a campaign to invade and conquer the state, setting itself up as a ruling dynasty. In these cases, tribes lose their tribal characteristics and become a ruling elite. However, if a nearby state gains strength and expands its territorial control, it may overrun and defeat the tribe, encapsulating it, incorporating it, and even assimilating it.
