And are you really saying that you think sub-saharan Africans were in Egypt thousands of years ago in large numbers and that they invented Science, Astrology, Mathematics, Language/Writing, Medicine, the Calender - then for some mysterious reason moved south of the Sahara to became a primitive culture while everyone else took credit for their great accomplishments and hid it by destroying the noses off of a statue? Come on man, this sounds like some Pewep level shit right here.
The Egyptians weren't sub-saharan. They were Saharan. There's evidence they originally lived in what is now the Sahara, which was green back then (evidence from river beds and fossils) but with increasing desertification, they moved west about 7000BC and settled on the Nile Delta.
They invented their culture by themselves, though they may have pinched ideas about agriculture from the Babylonians and Sumarians (who developed it about 10,000 years ago).
Egypt is the "source" for Mediterranean cultures. The Phonecians (modern Lebanese), the Syrians and the Greeks all copied them. Prior to the Greek encounter with Egypt as migrant workers in the 6thC BC, Greek statues were only tiny things no more than a foot high. After the encounter, the Greeks produced big statues known as Kouri - they have the same stiff Egyptian look as carving from stone without making the statue break due to imbalance hadn't been worked out and it was easier to make them like pillars, and it's clear that they pinched the technique from the Egyptians. The breakthrough by the Greeks for statues depicting movement didn't happen till 500BC.
Sigmund Freud (Jewish himself) even argued that the Jews were actually Egyptian followers of Akanaten. Akanaten if you recall, was the Pharoah who invented a monotheistic religion based on the Aten (the sun), and all went well till he had a bout of bad luck - family members dying, famines etc. He decided that it was all the fault of people not worshipping the Aten properly and carried out a series of murderous reprisals on his own people. The Egytians were so alarmed at this behaviour (untypical of the sedate calm that Pharoahs were supposed to have) that when Akanaten died, they moved the capital back to Thebes from Amarna, restored the old multi-god system each with their own priest (and which gave people the chance to choose which god to patronise according to their personal tastes), and banned Atenism as being dangerous and leading to public murders Akanaten-style.
Freud theorised that there were still some stubborn Aten worshipers remaining despite the restoration of the old system, and they were persecuted out of fear that what happened under Akanaten would reoccur, and finally chased out of Egypt (led out by Moses).
It's an interesting theory and explains how monotheism started, and why the Jews have a founding myth of persecution. But according to Freud's theory, they weren't a different race, they were just Egyptians who diverged religiously.
Anyway, I digress. Modern Egyptians are descended from ancient Egyptians (the DNA proves this). The "black people" Charles Martel mentions on Egyptian murals are the Nubians (modern Ethiopians) whom the Egyptians traded with (but didn't enslave). But both the Egyptians and the Nubians are Africans, they weren't from elsewhere. As for using pictures of Nefertiti to prove Egyptians weren't African - she was a Mittani princess married to Akanaten (the Mittani area is in present day Syria).
There seems to be confusion because there is huge genetic difference in Africa and people look different throughout that continent. But recall that it's the first home of homo sapiens and it is also a VAST continent. You could fit several North Americas within it, and populations spreading out would get isolated and evolve differently according to their particular environment.