Usually, more than four consecutive notes rising in pitch indicates foreign influence, except for some cases as the music of Bemba tribe.
The diversity of Bantu Music is a consequence of common racial heritage in areas of comparative isolation.
Employers and chiefs used to encourage them, and they are sometimes accompanied by dance used to produce works, as the origins of Malipenga, based upon military drill.
In areas like the tropical forests of the Congo Basin, trees offer a resource for the elaboration of drums.
Meanwhile, the music of Zulu tribes doesn't use drums due to the lack of material on the grazing grounds of Natal.