Speaking of civilized nations before 1500 A.D. (as this is before mass immigration took place and before many people lived on the left part of the world) , why is it that all civilizations have advanced besides African nations (except for Egypt, but that doesn't really count as African). Examples: (middle east) Turks, Saracens, Persians, Byzantines, (europe) Britons, Franks, Goths, Teutons, Celts, Vikings, (east asia) Japanese, Mongols, Chinese. None of which were in Africa. Why didn't they advance?