Конго Демократиялық Республикасының Касаи-Ориенталь провинциясы

Province of the Democratic Republic of the Congo
the similarly named, but larger province (1966–2015)

Kasaï Oriental (French for "East Kasai") is one of the 21 new provinces of the Democratic Republic of the Congo created in the 2015 repartitioning. Kasaï Oriental, Lomami, and Sankuru provinces are the result of the dismemberment of the former Kasaï Oriental province. Kasaï Oriental was formed from the Tshilenge district and the independently administered city of Mbuji Mayi which retained its status as a provincial capital. The new province's territory corresponds to most of the historic Sud Kasaï province which existed in the early period after independence between 1963 and 1966.

Kasai Oriental is inhabited by members of the Luba tribe. Congo obtained independence from Belgium in 1960. 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. After being repulsed, the Congo occupied the province in September 1961. Several thousand people were killed during the "pacification" of South Kasai, which lasted through the spring of 1962. 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. This is the largest accumulation of diamonds in the world, more concentrated than those at Kimberley, South Africa. Mbuji Mayi handles most of the industrial diamonds produced in the Congo.

French is the official language. Tshiluba is one of the four national languages of the Democratic Republic of the Congo. Tshiluba is spoken by about 6.3 million people in the Kasai Oriental, Kasai Occidental and Kasaï Central provinces.