Mitumba range extends from the south-eastern frontier of the colony, in a north-easterly direction towards Lake Tanganyika, and northwards along the western shore of that lake, past lakes Kivu and Albert Edward to Albert Nyanza, forming the western edge of the western or Albertine rift-valley. This long mountain chain has numerous local names. It varies in altitude from 5000 to 10,000 ft. The eastern escarpment is precipitous, but on its western face it slopes more gently into the Congo basin. North of the Lukuga river the main chain throws out into the central zone, in a north-westerly direction, a secondary range known as the Bambara Mountains, which forms one of the boundaries of the Manyema country. The interior or lake zone is a high plateau with an average elevation of 3000 ft. above sea-level.
The central zone dips with a westerly inclination from the Mitumba Mountains towards the western edge of the plateau. It is described as “a country of alluvial plains, without any marked mountain features, very well watered, covered with forests and wooded savannahs” (A. J. Wauters). The forests occupy the river valleys and are densest in the east and north-east of the state. In these primeval forests the vegetation is excessively rank; passage has to be forced through thick underwood and creeping plants, between giant trees, whose foliage shuts out the sun’s rays; and the land teems with animal and insect life of every form and colour. Describing the forests of the Manyema country, west of Lake Tanganyika, David Livingstone wrote: “Into these [primeval forests] the sun, though vertical, cannot penetrate, excepting by sending down at mid-day thin pencils of rays into the gloom. The rain water stands for months in stagnant pools made by the feet of elephants. The climbing plants, from the size of a whipcord to that of a man-of-war’s hawser, are so numerous, that the ancient path is the only passage. When one of the giant trees falls across the road, it forms a wall breast high to be climbed over, and the mass of tangled ropes brought down makes cutting a path round it a work of time which travellers never undertake.” This description is equally applicable to the forest region extending eastward from the mouth of the Aruwimi almost to Albert Nyanza. This forest covers an area of some 25,000 sq. m., and into a great part of it the sunshine never enters. It is known variously as the