A Cluster of some eighteen small tribes, numbering in all some 70,000 people, which lives on the rolling heights between the rivers Kasai, Sankuru and Lulua in the Kasai province of the Congo, are called Kuba by their neighbours. They form a kingdom which is in fact a federation of tribes, dominated by a central group, the Bushoong, whose chief is king of the whole congeries. This federation was imposed by the Bushoong upon the other tribes by conquest or threat of arms during the course of the three last centuries. As with all conquest states of which this one, although a federation, is typical, the different tribes controlled do not all have the same culture. One group, comprising the central tribes, is similar in culture and language. It includes the Bushoong, Ngeende, Pyaang, Byeeng, and Bulaang tribes. Other tribes are culturally akin to this group. Still other tribes belong to the Lulua-Luba Kasai cluster. Among these the patrilineal Coofa and the matrilineal Kete may be mentioned. Finally, other tribes like the Ngoombe or Mbeengi participate in the general type of Mongo cultures. The social structure of all the Kuba tribes with the exception of Coofa and Mbeengi is matrilineal. They are grouped in matrilineal clans, which are divided in small autonomous residential lineages, which can be called clan-sections. Clan-sections of different clans make up a village. The village is ruled by a set of dignitaries and a general council composed of the clan-section heads. The tribes of the central group and the ones who are culturally akin to it group several villages in chiefdoms which are ruled by chiefs assisted by councils. In these tribes, with the exception of the Bushoong, different chiefdoms are united loosely on a tribal scale. The Bushoong, who are the most numerous, are constituted in one chiefdom only. The religion of all the tribes of this cluster is very similar. Ancestor worship is practically absent. There are beliefs in a Supreme Being, in nature spirits, and in spirits or forces which control charms. Furthermore, mention must be made for the whole congeries of tribes of a flourishing art, especially decorative art, which is expressed in weaving, matting, woodcarving, ironworking and even architecture.