Ancient Egyptian Hieratic writing.This was the second of the two major writing systems, the first being the largely ceremonial Hieroglyphics.
Hieratic was used for bureaucratic and mundane recordings.
Note vague similarity of Hieratic writing to latter-day Arabic.
In ancient Egypt , the ability to read and write, and therefore to manage the state, was a monopoly of the priestly caste and court officials.
This may account in part for the lack of transfer of vital skills from fleeing migrants headed southwards into West Africa for instance.
The Arabs invaded Egypt in 600 AD or thereabouts, causing massive disruption and southern migrations. 700 years previously Blacks had been forced to flee southwards following the Greek invasion of Egypt led by Alexander the Destroyer (known as the Great).
It is during these southern migrations that bands were led by the likes of Oduduwa, to settle in West Africa.
The Greeks and Arabs meanwhile appropriated much of the knowledge of Egypt, raiding te Great Library at Alexandria that held the very pinnacle of knowledge availabe to humanity at the time.
They proceeded over time, to make what was reserved for the few elite under the Egyptian dispensation, ie knowledge: writing, architecture, mathematics etc available to more and more of their people. The educated African elite, the 'big boys' would have been retained in Egypt by force or of their own accord. Which noble wants to flee down the Sahara with commoners, dodging slave raiders, snakes, and wild animals?
The commoners were led by the likes of Oduduwa to settle in places like Nigeria, and other groups had similar leaders, who led them to their current station. Probably accounts for why we have no great architectural wonders in West Africa (although lack of mountains for stone didn't help either).
It explains why we lacked the tradition of writing. Our ancestors were the peasants of Egypt - the ones forced to flee - like the refugees you see fleeing war in Somalia today, with few of them literate even today, talk less of back then.
But our Nile Valley heritage is discernible in language similarities with Medu Netr, the Ancient Egyptian language, and in other expressions of our culture, practices such as Divine Kingship, Libation, Bride Price, Masquerades, Circumcision, Ancestor veneration, Funerary practices - kings are still buried with treasure in Nigeria - as it was in Egypt etc etc.