We have talked about the division of pre-history and history before and how the beginning of writing sets the two apart.  We generally say that the pre-historic period ends around 3200 B.C. or so when the Sumerians started writing.  However, not all civilizations began writing at the same time.  I imagine that some sub-Saharan African groups, tribes from the Americas, etc. did not start writing until well after that time.  How do we refer to the periods in which these groups existed?  For example, say we are discussing African history, c. 500 A.D., where writing was not use used or invented.  Is this still called “pre-historic Africa” because that particular society did not yet know how to read/write?