Kwango River  The Cuango or Kwango () is a transboundary river of Angola and Democratic Republic of Congo. It is the largest left bank tributary of the Kasai River in the Congo River basin. It flows through Malanje town in Angola. The Kwango River basin has large resources of diamonds in the Chitamba-Lulo Kimberlite Cluster in Lunda Norte Province, discovered in the main river channel and on flats and terraces in its flood plains. The Rund Kingdom, which expanded to become the Lunda Empire, encompassed territory stretching from Kwango River to the Laupala. Its rulers pursued slavery trade. Lunda expansion in the valley promoted a common political and cultural heritage while also promoting slave trading, accounting for the low population densities between the Kwango and Kwilu rivers. The Portuguese colonized the Kwango River valley and replaced the Kingdom of Kasanje. The Kwango River was subject to a Portuguese treaty signing in Lisbon on May 25, 1891 and the Declaration of March 24, 1894. Cuango town, situated in Lunda Norte Province within the Cuango River valley, is considered to be “in the diamond heartland of northeastern Angola”, the richest diamond area in Angola. This town played an important role during the civil war as both Uniao Nacional para a Independencia Total de Angola (UNITA) and government forces attempted to seize and hold the city. UNITA surrendered the town to the government on 30 September 1997 as part of the Lusaka Protocol. The Cuango originates in the highlands of Alto Chicapa in the Angolan province of Lunda Sul, and flows south-north-west, crossing the border with the Democratic Republic of the Congo, and joining the Kasai River near the town of Bandundo. Thereafter, it empties into the Congo River. Rising in the Lunda plateau, the river forms a deep valley. It is long from its source to its confluence with Congo River, of which lies in Angola. The river drains a total catchment area of . Its right bank tributaries are the Wamba and Kwilu rivers. The Cuango has a number of falls and rapids. Navigability is mostly achieved in the lower reaches of the river, spanning a length of from its mouth to the Kingushi rapids. Partial navigation is also possible in the middle stretches of the river between Kingushi and the Franz Josef waterfalls over a distance of about .