It borders the provinces of Kasaï-Occidental to the west, Équateur to the northwest, Orientale to the northeast, Maniema to the east, and Katanga to the south.

Friction with Congo's other ethnic groups and encouragement by Belgian corporations hoping to keep their mining concessions led to the secession of the province of South Kasai as a separate state headed by Albert Kalonji.

The population of Mbuji-Mayi grew rapidly with the immigration of Luba people from other parts of the country.

The region in which Mbuji-Mayi is situated annually produces one-tenth in weight of the world's industrial diamonds, with mining managed by the Société Minière de Bakwanga.

The former Kasai-Oriental was divided into the three districts of Tshilenge, Kabinda, and Sankuru; and the two cities of Mbuji-Mayi and Mwene-Ditu.