The southernmost headstream of the Congo River rises in Zambia and flows west through its northern area firstly as the Chambeshi and then, after the Bangweulu Swamps as the Luapula, which forms part of the border with the Democratic Republic of the Congo. The Luapula flows south then west before it turns north until it enters Lake Mweru. The lake's other major tributary is the Kalungwishi River, which flows into it from the east. The Luvua River drains Lake Mweru, flowing out of the northern end to the Lualaba River (Upper Congo River).