Historical Dictionaries of Africa
There is generally a dictionary for each country in Searchworks.  Contents include name changes, maps, chronology, history, important people. Some examples -

Historical Dictionary of Ancient Egypt 

Historical Dictionary of Ancient and Medieval Nubia

Historical Dictionary of Eritrea

Historical Dictionary of Ethiopia

Historical Dictionary of Ghana

Historical Dictionary of Kenya

Historical Dictionary of Namibia

 Historical Dictionary of Nigeria

 Historical Dictionary of the Sudan

Historical Dictionary of Uganda
 

African Archaeology Information Online - Stanford Library Guide

• Online primary sources, African university resources, academic journals online. 

JSTOR World Heritage Sites - Africa
Includes
Asante Ceremonies Collection
Ashanti Stool Histories
British Institute in Eastern Africa, Axum Archive
British Institute in Eastern Africa, Engaruka Archive [Tanganyika]
British Institute in Eastern Africa, Kilwa Archive [Tanzania] 

Has books on South African rock art, pre-colonial Mozambique, early history of the  East African coast, Ghana, Mali, Great Zimbabwe, excavations in Mali, full text of Religion and Art in Ashanti by Robert Rattray, 1927