[4] The river begins in central Angola and flows to the east until it reaches the border between Angola and the Democratic Republic of the Congo, where it turns north and serves as the border until it flows into the DRC.

The Kasai basin consists mainly of equatorial rainforest areas, which provide an agricultural land in a region noted for its infertile, sandy soil.

It is greatly controversial that some of the local kingdoms that were along the Kasai River supported the slave trade.

These activities, though they occurred between the 18th and 19th centuries, left a lasting impact in the regions where they were most prominent, such as between the Kwango and the Kwilu rivers.

In fact, it is common to hear the phrase “the diamond heartland of North Eastern Angola” used in reference to the Kwango River valley.