286 AFRICAN POLITICAL SYSTEMS
to a certain group and not a member of it in relation to a different group. Lineages are thus essentially relative groups, like tribal sections, and, like them, also are dynamic groups. Therefore they can only be described satisfactorily in terms of values and situations. Nuer lineages are not corporate localized communities though their members often have an association with a locality and speak of the locality as though it were an exclusive agnatic group. Every Nuer village is associated with a lineage, and though the members of it often comprise a small proportion of the community, it is identified with them in such a way that we may speak of it as an aggregate of persons clustered around an agnatic nucleus. The aggregate is linguistically identified with the nucleus by the designation of the village community by the name of the lineage. It is only in reference to rules of exogamy and certain ritual activities that one needs to regard lineages as completely autonomous groups. In social life generally, they function within local communities, of all sizes from the village to the tribe, and as part of them. We cannot here discuss the ways by which residential groups become a network of kinship ties—marriage, adoption, and various fictions— but the result tends to be that a local group is a cognatic cluster round an agnatic core, the rules of exogamy being the operating principle in this tendency.
Nuer clans are everywhere much dispersed, so that in any village or camp one finds representatives of diverse clans. Small lineages have moved freely over Nuerland and have settled here and there and have aggregated themselves to agnatically unrelated elements in local communities. Migration and the absorption of Dinka have been circumstances favouring the dispersal and mixture of clans. Being a conquering, pastoral people and not having an ancestral cult, the Nuer have never been bound to any particular spot by necessity or sentiment.
Nevertheless, there is a straight relation between political structure and the clan system, for a clan, or a maximal lineage, is associated with each tribe, in which it occupies a dominant position among other agnatic groups. Moreover, each of its segments tends to be associated with a segment of the tribe in such a way that there is a correspondence, and often a linguistic identification, between the parts of a clan and the parts of a tribe. Thus if we compare Diagrams II and III and suppose clan A to be the dominant clan in tribe B, then maximal lineages B and C correspond to primary