The tribal unit is therefore divided spatially into mobile and structurally fragile local groups. The Yafar social system partakes of both dimensions simultaneously, but segmentation of patrilineages is often carried out by founding a collateral branch in another tribe, and marriage occurs both within the society and with outside groups: patricians, submoieties, villages and tribes may or may not find themselves allied by intermarriage. The relative instability of agnatic groups and the practice of marrying in as much as out mean that neither of these two complementary principles can be used as a criterion for defining the tribe. The choice of new names and the demarcation of separate territories give rise to new tribes within the confederation. The dominant metaphorical reference to the coconut palm inflorescence makes it possible to unite into one identity the various identities of each tribal group.