Black and white lantern Slide of Tanganyika Plateau - British South Africa. Part of Box 288, Britrish South Africa. Boswell Collection. Slide number 22 Tanganyika Plateau - The Itombwe Mountains (or Itombwe Massif, Plateau) are a range of mountains in the South Kivu province of the Democratic Republic of the Congo (DRC). They run along the west shore of the northern part of Lake Tanganyika. They contain a vast area of contiguous montane forest and are home to a rich diversity of wildlife.