principal affluent of the Niger River on its right bank in Mali, West Africa, formed by the confluence of the Baoulé and Bagoé headstreams 100 mi (160 km) east of Bamako. The Bani proper flows 230 mi northeast to the Niger at Mopti in the swampy Macina depression. It is navigable only in part. Within a savanna zone, the region derives its wealth from the cultivation of millet, rice, sorghum, and corn along the riverbanks and from cattle herding.