The Ajuran Sultanate was a Somali Muslim empire that ruled over large parts of the Horn of Africa in the Middle Ages. The empire left an extensive architectural legacy, being one of the major medieval Somali powers engaged in castle- and fortress-building. Many of the ruined fortifications dotting the landscapes of southern Somalia today are attributed to the Ajuran Sultanate’s engineers.

http://en.wikipedia.org/wiki/Ajuran_Sultanate

http://operationoverload.wordpress.com/2009/04/29/the-ajuuraan-dynasty-of-the-hawiyya/

http://en.wikipedia.org/wiki/Olol_Dinle

http://atlantablackstar.com/2014/10/24/10-african-kingdoms-no-one-talks-about-but-should/5/