The largest people of the equatorial forest: a family of Bantu-speaking farming, fishing and hunting communities (Nkundo, Ekonda, Bolia, Ntomba, Ndengese, Tetela, Kusu and kin) filling the great inner bend of the Congo. They built no single state; authority rested in villages and lineage federations, which is why the map's central basin has always read as blank.
Not an ending: the Mongo remain the largest ethnic bloc of the Democratic Republic of the Congo. The map hands off in 1885 to the Congo Free State, whose rubber regime and imported disease devastated the basin.
The standard scholarly reconstruction of how equatorial-forest societies (including the Mongo cluster) organised themselves without states; verified via Open Library /works/OL3452765W.
Ohio University monograph centred on the central-basin (Mongo) societies and the Free State rupture that ends this record; verified via Open Library /works/OL3482425W.