The Mangbetu live in the northeastern corner of Zaire. They are distinctive in that they are the founders of one of the few centralized political systems in Central Africa. The territory that was eventually ruled by Mangbetu stretched about 300 kilometers east from the Uele River Basin and about 150 kilometers north from the Nepoko River. The number of people under Mangbetu control has been estimated at between 80,000 and 150,000. A 1959 census reported about 150,000 people in Mangbetu territories, and a 1985 count lists 650,000 Mangbetu speakers in Zaire.
The land occupied by the Mangbetu is a transitional zone in which environmental conditions vary considerably from north to south. Within 200 kilometers north to south, rainfall patterns range from almost no dry season to a dry season of three to four months; vegetation ranges from tropical forests, to forest-savanna mixture, to gallery forests, to wooded savanna. In this ecological zone, there is a variety of wild plant and animal life that exceeds that of the more uniform forest in the south or the savanna in the north. The Mangbetu, for example, traditionally hunted both the okapis of the forest and the zebras of the savanna.
A large range of domesticated plants can be found in the region as well. The long annual rainy season provides plenty of moisture for crops. In the dry season, there is ample time to cut down, dry, and burn trees for gardening. Numerous forests provide land for shifting agriculture. Regularly planted crops include grains (e.g., sesame, millet, maize), African and Asian yams, oil palms, sweet manioc, and the Mangbetu staples—sweet potatoes and plantain bananas.
The favorable environment of the forest-savanna ecosystem has been attractive to a large variety of human groups. Immigrants from east and west tended to remain in this abundantly rich area rather than to move on. Immigrants from the north were drawn to the area by its resources and were blocked from moving farther south by the forest barrier. The resulting clashes and intermarriages have contributed to the region's ethnic and cultural variety. There are at least fifteen dialects belonging to three different language families, which, in turn, are parts of two major linguistic groupings (Keim 1979). The Mangbetu, along with five other groups, speak the Kere language (more often known as "Mangbetu"). Kere is classified as being in the Central Sudanic Language Family, which is part of a larger grouping of Chari-Nile languages.