The Egyptian empire spanned Tens of thousands of years. Previous estimates showed the great pyramids being buil anywhere from 4 to 7 thousand years ago. They now believe it to be closer to 10 thousand years ago and I believe the sphinx even older, like 14 thousand years ago.
One recent factoid I read put it like this: more time has passed between the time of the completion of the great pyramid to the birth of Cleopatra than has passed from the birth of Cleopatra to today.
The Egyptian empire was already in decay by the time pf Cleopatra. Later era's or Dynasties of the empire appeared in southern egypt. And the pharoahs , queens and armies were indeed african. They wete marked by having no infrastructure or wealth or valuable commodities and produced no architecture. The monuments they did have were left over from previous, more prosperous dynasties. Fact.