Anthropologists customarily use the term ‘tribe’ to designate two realms of different yet connected facts. On the one hand, nearly all of them make use of it to distinguish one type of society among many, one specific mode of social organization which they compare to others—’bands,’ ‘States,’ etc. There is, however, a lack of unanimity on this point, an outcome of the imprecision, the haziness of the criteria selected to define and to isolate these various types of society. But the discord is deeper yet with respect to the second use of the term ‘tribe,’ when it is used to designate a stage in the evolution of human society.