Kasai region in the context of "Lomami Province"

South Kasai (French: Sud-Kasaï) was an unrecognised secessionist state within the Republic of the Congo (the modern-day Democratic Republic of the Congo) which was semi-independent between 1960 and 1962. Initially proposed as only a province, South Kasai sought full autonomy in similar circumstances to the much larger neighbouring state of Katanga, to its south, during the political turmoil arising from the independence of the Belgian Congo known as the Congo Crisis. Unlike Katanga, however, South Kasai did not explicitly declare full independence from the Republic of the Congo or reject Congolese sovereignty.

The South Kasaian leader and main advocate, Albert Kalonji, who had represented a faction of the nationalist movement (the Mouvement National Congolais-Kalonji or MNC-K) before decolonisation, exploited ethnic tensions between his own ethnic group, the Baluba, and the Bena Lulua to create a Luba-focused state in the group's traditional heartland in the south-eastern parts of the Kasai region. As sectarian violence broke out across the country, the state declared its secession from the Congo on 9 August 1960 and its government and called for the Baluba living in the rest of the Congo to return to their "homeland". Kalonji was appointed president. Although the South Kasaian government claimed to form an autonomous part of a federal Congo-wide state, it exercised a degree of regional autonomy and even produced its own constitution and postage stamps. The state, supported by foreign powers, particularly Belgium, and funded by diamond exports, managed numerous crises, including those caused by the large emigration of Luba refugees, but became increasingly militarist and repressive.