Great monuments and buildings.
http://www.cnn.com/2013/06/27/travel/rock-churches-lalibela-ethiopia/index.html
Evidence of written language
https://www.britannica.com/art/Ethiopian-literature
Looks like those rock churches were carved because of the influence of Christianity, not from the mythological African empire. And the literature was mostly translated and copied from other languages.
So what influences did this have on the rest of the world? What did they contribute to humanity or science?