FFROM THE BEGINNING OF THE NINETEENTH CENTURY to the global depression of the 1930s, the different regions of Africa experienced gradual but monumental change. The transatlantic slave trade declined and practically disappeared by the late 1860s. In the early nineteenth century Islam expanded its influence south of the Sahara, but Africa generally remained free of European political control. After about 1880 Africa was divided and largely conquered by Europeans, and by 1900 the foreigners were consolidating their authoritarian empires.