Kin Groups and Descent. Three social groupings are of primary importance in Purum society: the family; the subsib (social unit composed of several families); and the sib (composed of several subsibs). The sib and the family are the oldest of these three constituent groups. The Purum are divided into five exogamous sibs: Marrim, Makan, Kheyang, Thao, and Parpa. Each of these (with the exception of Parpa) is Divided into subsibs. Each sib is headed by a pipa (leader or head) who functions in a similar capacity for one of the subsibs. Fourteen subsibs were noted by Das in 1945. Each one is headed by its own pipa. The sib has one major responsibility—the regulation of marriage. The members of a subsib consider themselves to be blood relatives: the relationship of its members to one another is more intimate than that Between members of the sib. It has limited political, economic, and religious functions. At the time of Das's research, these units were no longer strictly exogamous; the rule of exogamy was strictly observed only at the level of the subsib. Exogamy at the subsib level is based on that at the sib level. Purum sibs are socially graded, but this gradation does not have an Impact on the selection of marital partners (e.g., there is no Evidence of hypergamy). Patrilineal descent obtains within the sib and subsib.
Kinship Terminology. Sudanese-type kinship terminology is employed for first cousins.