This chapter describes the circulation of ideas among Africans south of the Sahara, and explores those ideas which travelled across the frontiers. The great expansion of trade in much of sub-Saharan Africa during the nineteenth century had caused free Africans to move further from home than ever before. Languages were learned, and some, such as Hausa, Swahili or Lingala, became lingua francas. Religious cults acquired new followings; wars of conquest extended fields of political allegiance. Colonial conditions generated new routes for the circulation of people and ideas; they also fostered new channels of expression. Colonial rule and capitalism created opportunities for some, but for many they disrupted accustomed ways of earning a livelihood; they spread disease and aggravated jealousy and greed. Christianity claimed to offer salvation to all, but in practice could easily seem indifferent to African worries, contemptuous of African custom, and preoccupied with perpetuating white domination.