Barotseland (Lozi: Mubuso Bulozi) is a region between Namibia, Angola, Botswana, Zimbabwe including half of eastern and northern provinces of Zambia and the whole of Democratic Republic of Congo's Katanga Province. It is the homeland of the Lozi people or Barotse, or Malozi, who are a unified group of over 46 individual formerly diverse tribes related through kinship, whose original branch are the Luyi (Maluyi), and also assimilated Southern Sotho tribe of South Africa known as the Makololo. The Barotse speak siLozi, a language most closely related to Sesotho. Barotseland covers an area of 252,386 square kilometres, but is estimated to have been twice as large at certain points in its history. Once an empire, the Kingdom stretched into Namibia, Angola, Botswana, Zimbabwe including half of eastern and northern provinces of Zambia and the Democratic Republic of Congo's Katanga Province. Under the British colonial administration, Barotseland was a Protectorate of the British Crown from the late 19th-century. The Litunga, the Lozi word for the king of Barotseland, had negotiated agreements, first with the British South African Company (BSAC), and then with the British government that ensured the kingdom maintained much of its traditional authority according to the Litunga. Barotseland was essentially a nation-state, a protectorate within the larger protectorate of Northern Rhodesia. In return for this protectorate status, the Litunga gave the BSAC mineral exploration rights in Barotseland. In 1964, Barotseland became part of Zambia when that country achieved independence. However, some people claim that Zambia has violated the Barotseland Agreement 1964, and seek independence from Zambia. In 2012, a group of traditional Lozi leaders, calling itself the Barotseland National Council, called for independence; other tribal chieftains oppose secession, however. Its heartland is the Barotse Floodplain on the upper Zambezi River, but it includes the surrounding higher ground of the plateau comprising all of what was the Western Province of Zambia.