[quote name='caffeine' date='23 June 2010 - 12:41 AM' timestamp='1277278878' post='161724']
...it's pretty clear from looking at ancient Egyptian art that there were dark- and light-skinned Egyptians.[/quote]
It is not clear at all. The Egyptians remained a fairly insular race, genetically, until the time of the conquests by Greeks and later Romans. they did have relationships in Namibia, but there is not evidence of any migrations of people, or mingling of cultures.
Sub-saharan civilizations, pre-contact were not builders, and did not build structures ntended to last for a long period of time. On the east coast, the Arab immigrants who came to Africa around 800 AD, did build and did so along the same lines as they had in Arabia. there was also a spread south across the Sahara from Mediterranean that increased as Islam was spread.
The total lack of writing, necessary to express and promote ideas is a severe detriment to what we call "civilization". Greek civilization is represented by Plato, not the conquests of Alexander. It is represented by the inredible distance in years and miles that Greek culture has spread. there are no cultures in Sub-saharan Africa that show any signs of such attributes of civilization.
As I pointed out, this is also true of Germany and many other areas, and you see no such attempts to create a fictional past.
Your own arguments defeat your point. In Britian many, many Roman remains are found, both stone and many of wood. But the long term occupation and the wealth of evidence for a civilized society exist. Great Zimbabwe was begun around 1000AD. What was its purpose, who lived there, what did they think; these are the attributes that establish a society as civilized.
Sub-saharan Africa, prior to the arrival of Asian and Europeans, was not, not had it been, civilized. The why has many parts. Sub-saharan Africa was very poor in grain crops. Grain crops ar condusive to long term storage, alleviating famines and fostering trade between groups. Yes, there was farming, but largely of parishables which contribute to famines. A good example of this is Ireland. In the early 1700s, the British landowners moved the economy to potatoes for the English economy. The loss of animal husbandry and other grain crops resulted in the potatoe famine of the later 1800s.