I can answer for CocoGuy(Espresso) what is meant by advanced civilizations.
Timbuktu's long-lasting contribution to Islamic and world civilization is scholarship. Timbuktu is assumed to have had one of the first universities in the world. By the 14th century, important books were written and copied in Timbuktu, establishing the city as the centre of a significant written tradition in Africa. Historic descriptions of the city had been around since Leo Africanus' account in the first half of the 16th century, and they prompted several European individuals and organizations to make great efforts to discover Timbuktu and its fabled riches.
The Songhai Empire, also known as the Songhay Empire, was a pre-colonial West African trading state centered on the middle reaches of the Niger River in what is now central Mali.Considered one of the greatest African empires, from the early fifteenth to the late sixteenth century, Songhai was also one of the largest empires in West Africa, stretching all the way to present-day Cameroon. With several thousand cultures under its control, Songhai was clearly the largest empire in African history.
As early as 8th Century B.C.E. The Axumite Kingdoms (Ethiopia and Eritrea) that rose in the first century can be considered the first line in a series of successor Kingdoms that remained uninterrupted until modern times.
Did you know that people from around the world, ie Semites, Greeks and Romans and even East Asians came to Timbuktu to study at the Universities there? I'll bet you were thinking the slave trade was the best thing to happen to Africans, huh? While it's true the Africans had other Africans in slavery, it was nowhere near as brutal as the slave experience under whites. The slaves in Africa were still treated as humans, could own land and weren't separated from their families. They weren't systematically demeaned and once they were freed (they weren't slaves for life), they weren't treated as second class citizens. Also, they were enslaved as prisoners of war, not kidnapped or stolen from their homes. I hope you are now enlightened.
Oh,I see CocoGuy didn't need my assistance!