The more than 300 thousand square kilometers of these two regions are centered around the headwaters of the Kasai River(4). The entire area is low plateau, highest in the south.
The river flows into the south center of the Western Kasai Region, and exits westward. Its chief right bank tributaries are the Kaongeshi and the Lulua, both entering from the south of the western region, and the Sankuru. This last river, formed by the Lubashi and Lufu rivers in the south, cuts through the two regions' heart before joining the Kasai at the western border. It is after receiving the Sankuru that the Kasai becomes navigable.
The only important left bank feed is the Loange, forming much of Western Kasai's western boundary.
The easternmost part of this zone is drained by other tributaries of the Congo, most significantly the Lomani, which marks much of the eastern edge of Eastern Kasai.
More than ten million people live here, the majority of them(5) speaking the Central (or Kasai) dialect of Luba. Many others learn it. Religion probably follows the national pattern.
Mbuji-Mayi is the only city with a million residents.
Sometime after 500 B.C.E., Bantu people spread into this area, probably from the northeast. Luba, a Bantu language, spread here from the southeast(6) under the rule of the Belgians(7), who used the Luba as laborers and civil servants.
northwest
northeast
east
southeast
southwest
west
(1) Formerly Zaire. Also called Kinshasa Congo.
(2) Occidental in French.
(3) Oriental in French.
(4) The ninth or tenth longest river in Africa. It is a tributary of the Congo.
(5) More than seven in ten.
(6) Or at least gained prominence under the influence of the southeast.
(7) Perhaps also earlier under the Luba Empire to the southeast.