Variety of experience is perhaps the most striking feature of the history of eastern Africa during the seventeenth and eighteenth centuries. Along the coast this vast region stretches southwards from Mogadishu to the mouth of the Zambezi river. Inland it extends from the southern Ethiopian escarpment and the southern Sudan down along the western edge of the great lakes region, across the corridor between Lakes Tanganyika and Malawi, and then follows the Luangwa river until its confluence with the Zambezi. In the northern interior – including most of modern Kenya, Uganda, Rwanda, and Burundi – both Nilotic-speaking and Bantu-speaking peoples were still isolated from the coast, still able to resolve their problems without having to confront the economic and allied challenges that would emanate from the coast in the nineteenth century. In the central interior – encompassing most of the Tanzanian mainland – it is possible to see a gradual transition by the end of the eighteenth century from the northern pattern of historical development to that of the southern interior – comprising what is today southern Tanzania, northern Mozambique, Malawi, and the eastern-most region of Zambia – where the main challenge to the Bantu-speaking peoples was the growth and impact of international trade. On the coast, the various Swahili-speaking communities were already concerned to preserve what they could of their ancient political and economic independence from two successive sets of overlords, the Portuguese and the Omani Arabs. Yet throughout these two centuries it is also possible to discern common processes at work in these four regions of eastern Africa.

Two great divides have marked the last seven millennia in Africa: the transition to food production and the modern revolution in the means of communication. The impact of these innovations was by no means felt simultaneously throughout the continent. A few people living in the most inhospitable areas have yet to participate in the first, but the vast majority of Africans were already pastoralists or agriculturalists long before the end of the first millennium AD. The impact of the second, nineteenth-century revolution was more immediate, though certain aspects of communications were already being influenced by much earlier developments. In successive millennia, trade-links within Africa had been profoundly affected by the Phoenician, Arab and Portuguese explorations of, respectively, the North African, Indian Ocean and Atlantic coasts of Africa. North of the equatorial forests, the camel and the horse had increased man's mobility, and Islam had brought literacy to a restricted few. But until the transformation which began, not with colonial rule, but with the steamers, railways, telegraph, vernacular bibles and newspapers of the nineteenth century, communications throughout most of sub-Saharan Africa had remained largely dependent on oral messages and human porterage. Until the nineteenth century, the pace of change was not dependent on an alien technology. The main lines of communication lay not with the outside world, but within the continent itself.

Compared with these watersheds, the year 1600 marked no noticeable break in continuity; yet in some important respects the seventeenth and eighteenth centuries in Africa do constitute a period of transition, distinct from both the sixteenth and the nineteenth centuries.