Chapter 4 represents the beginning of Evans-Pritchard’s second stated goal of analyzing the social structures of Nuer culture, beginning with its political structures. Nuer tribes, which are the largest political units in their society, are segmented into sections of various sizes. A single tribe might be segmented into two primary sections, and those primary sections might be segmented into three secondary sections, which then might be segmented into tertiary sections, below which are the level of villages. These segments often have definitive qualities like a distinctive name and a well-defined territory, much as the tribe at large does. Evans-Pritchard continues his use of sketches and charts to supplement his text, and his illustrations in Chapter 4 are particularly helpful in giving a visual presentation of an abstract idea, using subdivided rectangles to represent the segmentation of tribal units.

As with tribes, the identity-values of tribal segments are often defined in opposition to other segments in the same system. Local attachments, at the level of villages and tertiary segments, constitute the strongest affective attachments for the Nuer. Their allegiances to larger tribal groups are often only evident when common action at those levels is called for, usually in opposition to other tribes or primary segments: Thus there is [.