In case you would want to brush up on your knowledge of the history of Africa, you can download Unesco’s ebooks on the subject for free online. The eight volumes:
Volume I: Methodology and African Prehistory
Volume II: Ancient Civilizations of Africa
Volume III: Africa from the Seventh to the Eleventh Century
Volume IV: Africa from the Twelfth to the Sixteenth Century
Volume V: Africa from the Sixteenth to the Eighteenth Century
Volume VI: Africa in the Nineteenth Century until the 1880s
Volume VII: Africa under the Colonial Domination 1880-1935
Volume VIII: Africa since 1935
For more information about this project (which started in 1964) click here.