I will spare you the entire song - I'm specifically referring to this section, where he's talking about African history:
Be, be'fore we came to this country
We were kings and queens, never porch monkeys
There was empires in Africa called Kush
Timbuktu, where every race came to get books
To learn from black teachers who taught Greeks and Romans
Asian, Arabs and gave them gold when
Gold was converted to money it all changed
Money then became empowerment for Europeans
The Persian military invaded
They heard about the gold, the teachings and everything sacred
Africa was almost robbed naked
Slavery was money, so they began making slave ships
Egypt was the place that Alexander the great went
He was so shocked at the mountains with black faces
Shot off [sic] they nose to impose what basically
Still goes on today, you see
I know he confused Alexander the Great with Napoleon about shooting off the nose of the Sphinx, but other than that, how would you grade him?
Was Africa really the bastion of knowledge he claims it was, with Greeks, Romans, Arabs, and Asians flocking to Africa to learn and even acquire (seemingly proprietary) books?
Was Africa basically "robbed naked" by the Persian military?
Was gold really not used as money in Africa prior to the Europeans?
Obligatory link to the part of the song I'm referencing.
Timbuktu certainly was a place where people went for the books, but most definitily not the Greeks or Romans. It's libraries were founded in the 16th century by Askia al-Hajj Muhammad.
Kush is ancient Ethiopia. Slaves never came from there. It was a very powerful kingdom that opened up on the Red Sea. There was hardly ever a Red Sea Slave route, African Americans almost definitely never came from there. Reading the wiki on Ethiopian slavery, in fact, they had a long tradition of enslaving the more 'negroid' looking tribes. Exports were of young Ethiopian maidens as highly valued concubines to Arabia and some laborers and eunuchs also to Arabia.
Persia also never invaded Kush. They invaded Egypt so maybe Nas was talking about Alexandria. But I don't think the order of Kush ruling Egypt, Persia invading Kushite Egypt and Alexander the great invading Egypt and founding Alexandria allow for that. 700BC to 500BC those three things happened as listed.