South at the top?
I think you will find that in Ancient Egypt - Upper Egypt - the source of the Nile was at the top. As we all know water flows downhill, so the top of Egypt was at the top of the map and the Nile Delta was at the bottom. This may be where you came across the idea - I've looked for examples of maps on the Internet but all the maps I've found are modern interpretations, designed to give details of ancient sites rather than showing how the world was seen at the time.http://kroeber.anthro.mankato.msus.edu/prehistory/egypt/maps/mainmap.html

I should imagine that the source of a river was as good as anything to put at the top of a map in ancient civilisations.

I particularly like the Peter Projection which gives much better idea of the size of Africa.