It extends from the Cameroon Highlands in the west, across central Cameroon and the southern Central African Republic to southwestern South Sudan and northeastern Democratic Republic of the Congo, where it is bounded on the east by flooded grasslands of the Sudd, the eastern block of the East Sudanian savanna, and the Albertine Rift montane forests.

Rainfall is generally higher in the south, in the transition to the Congolian forests, and lower in the north at the edge of the Sudanian savanna.

Typical gallery forest trees include Berlinia grandiflora, Cola laurifolia, Cynometra vogelii, Diospyros elliotii, Parinari congensis, and Pterocarpus santalinoides.

Remnants of semi-evergreen forest are found in the south, composed mostly of typical Congolian species like Afzelia africana, Aningeria altissima, Gambeya perpulchra, Cola gigantea, Morus mesozygia, and Khaya grandifoliola.

Trees, including Annona senegalensis, Burkea africana, Combretum collinum, Hymenocardia acida, Parinari curatellifolia, Stereospermum kunthianum, and species of Vitex and Strychnos, form open-canopied woodlands or are scattered in grassy savannas.

Grazing mammals include the African bush elephant (Loxodonta africana) and African forest elephant (Loxodonta cyclotis), Kordofan giraffe (Giraffa camelopardalis antiquorum), African buffalo (Syncerus caffer), eastern giant eland (Taurotragus derbianus gigas), lowland bongo (Tragelaphus eurycerus eurycerus), waterbuck (Kobus ellipsiprymnus), Buffon's kob (Kobus kob kob), roan antelope (Hippotragus equinus), and red-flanked duiker (Cephalophus rufilatus).

Near-endemic mammals include Pousargues's mongoose (Dologale dybowskii), which also inhabits the Victoria Basin forest–savanna mosaic to the east, and the ochre mole-rat (Fukomys ochraceocinereus).