The Masai provide a classic example of the Nilo-hamitic linear age-group system. Many aye set names have heen recorded, particularly by Hollis at the turn of the century: the earliest, those of Krapf, dale back a further 50 years. The. dating of such sets has, however presented considerable difficulty. The situation is confused by the fact that the Kwavi, a branch of the Masai, practiced a parallel system, similar in ceremonial and political significance but with different group names; the differing origins of such names was not always appreciated and this led to the impression that the system had greater depth than in fact existed