A tribe is a social formation existing before the development of, or outside of, states. Many people use the term to refer to any non-Western or indigenous society. Some social scientists use the term to refer to societies organized largely on the basis of kinship, especially corporate descent groups (see clan and lineage). In some states, such as the United States and India, tribes are polities that have been granted legal recognition and limited autonomy by the state.
There are considerable debates over how best to characterize tribes. Some of this debate owes to likely differences between pre-state and contemporary tribes; some of this debate reflects more general controversy over cultural evolution and colonialism. In the popular imagination, tribes reflect a way of life that predates, and is more "natural", than modern states. Tribes also privilege primordial social ties, are clearly bounded, homogeneous, parochial, and stable. Thus, many believed that tribes organize links between families (including clans and lineages), and provides them with a social and ideological basis for solidarity that is in some way more limited than "ethnic group" or "nation." Anthropological and ethnohistorical research has challenged all of these notions.
In his 1972 study, The Notion of the Tribe, Morton Fried provided numerous examples of tribes the members of which spoke different languages and practised different rituals, or that shared languages and rituals with members of other tribes. Similarly, he provided examples of tribes where people followed different political leaders, or followed the same leaders as members of other tribes. He concluded that tribes in general are characterized by fluid boundaries and heterogeneity, are not parochial, and are dynamic.
Archeologists continue to explore the development of pre-state tribes. Current research suggests that tribal structures constituted one type of adaptation to situations where resources were plentiful yet unpredictable. Such structures were flexible enough to coordinate production and distribution of food in times of scarcity, without limiting or constraining people during times of surplus.
Fried, however, proposed that most contemporary tribes do not have their origin in pre-state tribes, but rather in pre-state bands. Such "secondary" tribes, he suggested, were actually modern products of state expansion. Bands are small mobile, and fluid social formations with weak leadership, that do not generate surpluses and can neither be taxed, nor support a standing army. Fried argued that secondary tribes develop in one of two ways. First, they could be created by states as means to extend administrative and economic influence in their hinterland, where direct political control could be too costly. States would encourage (or require) people on their frontiers to form more clearly bounded and centralized polities, because such polities could begin producing surpluses and be taxed, and would have a leadership responsive to the needs of neighboring states (a good example of this is the so-called "scheduled" tribes of the United States or British India). Second, they could be created by bands as a means to defend themselves against state expansion. Members of bands would form more clearly bounded and centralized polities, because such polities could begin producing surpluses that could support a standing army that could fight against states, and they would have a leadership that could coordinate economic production and military activities.
See also cultural evolution