At the beginning of the twentieth century the main engine of change in Central Africa was the British South Africa Company, founded by Cecil Rhodes. In 1889 it had received from the British government a charter to exercise powers of administration in the region. During the next decade its agents invaded most parts of the mineralised tablelands between the middle Limpopo, the Zambezi-Congo watershed and Lake Tanganyika; the Company thereby gained private possession of virtually all mineral deposits throughout the sphere assigned to it by international treaties. South of the Zambezi, in what from 1898 was called Southern Rhodesia, gold and the temperate climate of the uplands attracted white settlers, who seized much African land. North of the Zambezi, the Company's sphere consisted by 1900 of two territories: North-Western Rhodesia, with communications running south, and North-Eastern Rhodesia, with communications running eastwards to the Shire valley. They were united in 1911 to form Northern Rhodesia. In 1905 the western border of the Company's northern sphere, hitherto disputed by Portugal, was settled by arbitration. Its eastern border was formed by the highlands sloping down to Lake Nyasa (Malawi). These highlands, and the country straddling the route to the lake up the Shire valley, had been taken over by the Foreign Office and designated the British Central Africa Protectorate; this was transferred to the Colonial Office in 1904 and called Nyasaland from 1907. The territory contained dense clusters of population; there were no minerals of consequence but much land had been alienated by whites in the Shire highlands.