The Tawana state of northwestern Botswana can be seen as the least successful in incorporating other ethnic groups. Most of its population is Yei and Mbukushu by origin, related to riverine peoples in the Caprivi Strip, Angola, and Zambia to the north. Smaller numbers of Mbanderu and Herero have greater numbers of close relatives across the border in Namibia. The Subiya along the Chobe, closely related to people in the Caprivi Strip and Zambia, were excluded from the Tawana tribal reserve by the British.