Uíge Province
In this section of the river, there are two significant tributaries to the great Congo River, both on the left or south side. The Kwilu River originates in the hills near the Angolan border and enters the Congo some 100 km upstream from Matadi. The other being the Inkisi River, that flows in a northerly direction from the Uíge Province in Angola to the confluence with the Congo at Zongo some 80 km downstream from the twin capitals.