At the beginning of the nineteenth century, the Mangbetu were only one of many small groups of people that were settling on the northern edge of the Zaire rain forest. At that time, the Mangbetu leader, Nabiembali, gathered a following of warriors and moved north across the upper Bomokandi River to subdue groups of Mangbele and Mabisanga. Not long afterward, he continued Mangbetu expansion by conquering other peoples in the area, among them groups of Madi, Bangba, Mayogo, Mayvu, Makango, and Barambo. The major significance of Nabiembali's conquests was that he incorporated non-Kere-speaking peoples into his kingdom. His conquests represented the first time that power had been wielded on a territorial basis.
The Mangbetu are basically patrilineal. At the same time, the maternal uncles of a man are very important. It was formerly a common practice for a strong nephew to be accepted as a ruler over his maternal kin. The nephew's son then became heir to his father's power. Tied in with these practices was the tradition of giving women to unrelated groups or exchanging women with them. This practice was accepted throughout the region as a form of peacemaking or alliance, but Nabiembali—and the Mangbetu who followed him—turned the custom into an institution of control over the many ethnic groups that were represented among their subjects. One of the primary advantages of this practice was that it could give a weak clan a strong leader, through the clan's maternal ties; however, Nabiembali used the practice in reverse. He developed a strategy of marrying many wives, not only to increase productivity, display his wealth, and have many sons, but also to legitimize his conquests and extend his control. His policy worked to the extent that some of his sons were accepted as rulers among their mothers' peoples. However, because his sons sought to extend their own power and the influence of their maternal clans (over which they ruled), and because they challenged the authority of their father, both centralized power and the extent of Mangbetu rule were eventually weakened.
The justification of Mangbetu leadership was related to two concepts, nataate and nakira. "Nataate," loosely translated, refers to one's capacity to do, or one's social skills. "Nakira" refers to one's intelligence or one's technical and mental skills. Nataate is the dynamic power that exists within a person and makes him respected by others. Nakira is the ability one has in almost any endeavor, but particularly in dancing, singing, and public speaking. The Mangbetu criterion for succession was a combination of hereditary links and ability. Superior nataate and nakira were considered seriously in the choice of a successor to the ruler; therefore, an incompetent firstborn son might be rejected in favor of a more competent younger brother. In practice, many succession problems resulted from this imprecise formula for the transfer of power.
The Mangbetu achieved a very high level of technological and material development, as indicated by early reports from European explorers. For example, Georg Schweinfurth, the first European to reach the area, visited Mbunza, the Mangbetu ruler, in 1870, and described thousands of subjects at Mbunza's court as well as hundreds of nobles and courtiers. Within the capital, there were many large buildings; smaller huts filled with animal skins, feathered hats, and necklaces; and an armory of iron spears, piles of knives, and hundreds of polished copper lances. Mbunza's household included musicians, eunuchs, jesters, ballad singers, dancers, and bodyguards. Surrounding the capital were large, cultivated fields and orchards of oil palms and other trees (Schweinfurth 1874).
Much of the Mangbetu material culture was probably borrowed from conquered peoples, but the Mangbetu encouraged the development of all the arts of the peoples under their control. Examples of their crafts include intricately forged chains and knives with carved ivory handles; geometric decoration of bodies, pots, mats, and houses; a distinctive coiffure that emphasized their artifically elongated heads; carefully carved stools, dishes, gongs, trumpets, and canoes; and finely formed human heads made out of clay and wood.