In acephalous political systems, no single head is recognised and order is maintained by means other than the state apparatus. This system has four sub-types, exemplified by four groups-the Central African Bushmen, the Yako of Nigeria, the Masai of East Africa and the Nuer of Sudan. In the first sub-type, order is maintained by the eldest of each band of Bushmen, hunters and gatherers. In the second sub-type, the village councils and in the third sub-type, age-sets take the responsibility of keeping order in society. In the fourth sub-type, order is kept on the basis of relations among lineages.