What is the main feature of tribal social structure?

According to Oxford Dictionary "A tribe is a group of people in a primitive or barbarious stage of development acknowledging the authority of a chief and usually regarding themselves as having a common ancestor.

D.N Majumdar defines tribe as a social group with territorial affiliation, endogamous with no specialization of functions ruled by tribal officers hereditary or otherwise, united in language or dialect recognizing social distance with other tribes or castes. According to Ralph Linton tribe is a group of bands occupying a contiguous territory or territories and having a feeling of unity deriving from numerous similarities in a culture, frequent contacts and a certain community of interests.

L.M Lewis believes that tribal societies are small in scale are restricted in the spatial and temporal range of their social, legal and political relations and possess a morality, a religion and world view of corresponding dimensions. Characteristically too tribal languages are unwritten and hence the extent of communication both in time and space is inevitably narrow. At the same time tribal societies exhibit a remarkable economy of design and have a compactness and self-sufficiency lacking in modern society.