THE NUER OF THE SOUTHERN  SUDAN	289
a severe ordeal and a series of rites connected with it. These initiations take place whenever there are a sufficient number of boys of from about fourteen to sixteen years of age in a village or district. All the youths who have been initiated in a successive number of years belong to one age-set, and there is a four-year interval between the last batch of initiates of one set and the first batch of the next set, and during this interval no boys may be initiated. The initiation period is open for about six years, so that, with the four years of the closed period, there are about ten years between the commencement of any age-set and the commencement of the set that precedes or succeeds it. The age-sets are not organized in a cycle.
Nuer age-sets are a tribal institution in the sense that, in the larger tribes at any rate, all the sections of a tribe have the same open and closed periods and call the sets by the same names. They are also the most characteristic of all Nuer national institutions, for initiation scars are the sign of their communion and the badge of their supremacy. Moreover, though each big tribe has its own age-set organization, adjacent tribes co-ordinate their sets in periods and nomenclature, so that the Western Nuer, the Eastern Nuer, and the Central Nuer tend to fall into three divisions in this respect. But even when a man travels from one end of Nuer-land to the other, he can always, and easily, perceive the set which is equivalent to his own in each area. The age-set system, therefore, like the clan system, whilst having a tribal connotation, is not bound by lines of political cleavage.
There is usually in each tribe a man whose privilege it is to open and close initiation periods and to give each set its name* This man belongs to one of those lineages which have a special ritual relationship to cattle and are known as 'Men of the Cattle'. He opens and closes initiation periods in his own district, and other districts of his tribe follow suit. Once a period has been opened, each village and district initiates its boys when it pleases. The age-sets have no corporate activities and cannot be said to have specific political functions. There are no grades of 'warriors' and 'elders' concerned with the administration of the country> and the sets are not regiments, for a man fights with the members of his local community, irrespective of age. In the rites of initiation there is no educative or moral training. There is no leadership in the sets.