Sotho-Tswana cattle chiefdoms (merafe) of the eastern Kalahari margin and the western highveld — Kwena, Ngwaketse, Ngwato, Tawana, Rolong, Hurutshe, Kgatla, Tlhaping and others — each ruled by a kgosi through the kgotla assembly from a large aggregated town. Segmentation from the senior Kwena line produced the Ngwaketse and Ngwato around 1530 and the Tawana at Lake Ngami later; the Difaqane and Boer expansion reshaped them before their chiefs negotiated British protection in 1885.
Not an ending: the Batswana merafe survive as the constitutionally recognised tribes of Botswana, seated in the Ntlo ya Dikgosi, with large Tswana populations in South Africa's North West province. The map hands off to the Bechuanaland Protectorate proclaimed in 1885.
The Ethnographic Survey of Africa volume on Tswana political organisation, the merafe and the kgotla; verified via Open Library (OL1170267W; 1992 revision OL15105484W).
Scholarly history of the Ngwato and Tawana chiefdoms through the decades ending in the protectorate; verified via Open Library (OL4957926W, ISBN 0838615376).