If I haven't been clear before, I personally could not give a crap about Cleopatra. The details of ancient history are literally academic (in the sense of having no practical or useful significance), at this point.
I just find an argument like this to be psychologically fascinating. You are arguing with insistence about the racial purity of someone who died thousands of years ago. I don't think that's how archeology works.
As for the focus on Ancient Egypt, European colonization, and the Transatlantic slave trade -- those are all taught as relevant to American history, so not surprising if they are relevant to African Americans. Yes, there is a great deal of world history (Africa and everywhere else) that is completely ignored by the general US population, and most individuals in the US. That's not a point that is only true when discussing issues related to black people, though.