The basic social and political unit among barbarian groups was the tribe or confederation, a group whose members believed that they were all descended from a common ancestor. Tribes were led by chieftains. The chief was the member recognized as the strongest and bravest in battle and was elected from among the male members of the most powerful family.

Closely associated with the chief in some tribes was the comitatus, or war band. These warriors swore loyalty to the chief, fought with him in battle, and were not supposed to leave the battlefield without him; to do so implied cowardice, disloyalty, and social disgrace. These oaths of loyalty were later more formalized in the development of feudalism (see Chapter 8).