UNESCO offers an extensive General History of Africa. You can download each book free of charge:
https://en.unesco.org/general-history-africa
Available languages are English, French, Arabic, Portuguese, Spanish, Italian, Fulfulde, Hausa and Swahili, but not all languages have each book translated in full. There are some languages which offer only the abriged version translated.
Here are some of the books offered on this site:
Methodology and African prehistory
https://unesdoc.unesco.org/ark:/48223/pf0000042225
Ancient civilizations of Africa:
https://unesdoc.unesco.org/ark:/48223/pf0000184265
Seventh-Eleventh century in English unabridged:
https://unesdoc.unesco.org/ark:/48223/pf0000184282
Twelfth-Sixteenth century in English unabridged:
https://unesdoc.unesco.org/ark:/48223/pf0000184287
All books are translated in their unabridged version in English, Arabic, French and Portuguese.
Happy reading!