On the coast, following the death, in 1856, of Sayyid Saʿīd, his erstwhile dominions in East Africa were split off from the imamate of Muscat. By 1873 the authority of the Āl Bū Saʿīdī sultans on Zanzibar itself became complete, although there were still revolts against them on the coast—particularly at Pate and Mombasa (where the Mazrui retained their preeminence despite successive defeats)—and at Kilwa, to the south. This arose chiefly from the sultan’s acceptance of the further measures against the East African slave trade pressed upon him by the British consul at his court. By the 1860s some 7,000 or so slaves were being sold annually in the Zanzibar slave market, but in 1873 a treaty with the British closed the market at Zanzibar, and Sultan Barghash, by two proclamations in 1876, reduced the export from the mainland to a trickle. As it happened, however, there was then a final period of unprecedented slaving on the mainland, where the trade in slaves had generally been closely connected with the trade in ivory and the demand for porters was still considerable.

Trade in the East African interior began in African hands. In the southern regions Bisa, Yao, Fipa, and Nyamwezi traders were long active over a wide area. By the early 19th century Kamba traders had begun regularly to move northwestward between the Rift Valley and the sea. Indeed, it was Africans who usually arrived first to trade at the coast, rather than the Zanzibaris, who first moved inland. Zanzibari caravans had, however, begun to thrust inland before the end of the 18th century. Their main route thereafter struck immediately to the west and soon made Tabora their chief upcountry base. From there some traders went due west to Ujiji and across Lake Tanganyika to found, in the latter part of the 19th century, slave-based Arab states upon the Luapula and the upper reaches of the Congo. In these areas some of those who crossed the Nyasa-Tanganyika watershed (which was often approached from farther down the East African coast) were involved as well, while others went northwestward and captured the trade on the south and west sides of Lake Victoria. Here they were mostly kept out of Rwanda, but they were welcomed in both Buganda and Bunyoro and largely forestalled other traders who, after 1841, were thrusting up the Nile from Khartoum. They forestalled, too, the coastal traders moving inland from Mombasa, who seemed unable to establish themselves beyond Kilimanjaro on the south side of Lake Victoria. These Mombasa traders only captured the Kamba trade by first moving out beyond it to the west. By the 1880s, however, they were operating both in the Mount Kenya region and around Winam Bay and were even reaching north toward Lake Rudolf.

Missionary activity

The revelations of these explorers, the example of David Livingstone, concern in western Europe over the East African slave trade, and the Roman Catholic and evangelical fervour that existed there inspired the invasion of the East African interior by a motley collection of Christian missionary enterprises. Johann Ludwig Krapf and Johannes Rebmann of the Church Missionary Society, who had worked inland from Mombasa and had, in the 1840s and ’50s, journeyed to the foothills of Mount Kenya and Kilimanjaro, were followed by a British Methodist mission. Roman Catholic missionaries reached Zanzibar in 1860 and settled at Bagamoyo in 1868. An Anglo-Catholic mission first tried to establish itself in the Shire highlands, then in 1864 transferred to Zanzibar. Anglican missionaries arriving in Buganda in the mid-1870s at the request of Kabaka Mutesa were soon followed by Catholic White Fathers—there and elsewhere on Zanzibar’s Tabora route—while the London Missionary Society sent men both to Unyamwezi and to Lake Tanganyika.

There were, of course, a number of localized religious movements among the peoples of East Africa during the 19th century. These included the Mbari cult among the Nyakyusa, the Nyabingi in Rwanda, and the Yakany movement north of Mount Ruwenzori. None of them, however, spread in quite the way that the Chwezi movement had earlier. Islam, on the other hand—spread widely at the instance of the Zanzibari traders and long established on the coast—had secured a scattering of converts in the interior as in the key kingdom of Buganda.

This was the scene onto which Christian missionaries first entered. Although by 1885 there were nearly 300 of them in East Africa, they did not initially win many converts, and those they at first obtained came only from among freed slaves and refugees from local wars. After 1880, however, they made important conversions in Buganda, and by the end of the century Christianity was spreading in the Lake Victoria area over most of the region in which the Chwezi movement had previously percolated—and before very long over a much larger area as well.

Partition by Germany and Britain

Philanthropic, commercial, and eventually imperialist ventures followed these evangelical endeavours. Nothing of great moment, however, occurred until 1885, when a German, Carl Peters, riding a tide of diplomatic hostility between Germany and Britain in Europe, secured the grant of an imperial charter for his German East Africa Company. With this the European Scramble for Africa began. In east-central Africa the key occurrence was the Anglo-German Agreement of 1886, by which the two parties agreed that their spheres of influence in East Africa should be divided by a line running from south of Mombasa, then north of Kilimanjaro to a point on the eastern shore of Lake Victoria. This began the extraordinary process by which the territories and subsequently the nations of East Africa were blocked out first upon the maps far away in Europe and only later upon the ground in East Africa itself. The agreement put the area to the north (most of modern Kenya) under British influence and the area to the south (Tanganyika; modern mainland Tanzania) under German influence. The Anglo-German Agreement of 1890 placed additional territory (most of modern Uganda) under British influence.

Kenya was proclaimed a British protectorate in 1895 and a crown colony in 1920. Most of what is now Uganda was formally proclaimed a British protectorate in 1894, with additional areas being added to the protectorate in the following years. Tanganyika was declared a German protectorate in 1891. During World War I, Britain captured the German holdings, which became a British mandate in 1920. Britain retained control of Tanganyika after World War II when it became a United Nations trust territory. Tanganyika gained independence in 1961 and in 1964 merged with Zanzibar, later taking the name Tanzania. Uganda gained its independence in 1962, and Kenya became fully independent in 1963.