The sixty century was a great watershed in the East African history -- a period of very rapid change and probably decline, in which the key ports simply ceased to exist and agricultural economy shrank. The culprit was almost certainly plague -- the same epidemic that devastated Europe and the Near East in the same fateful century. Indeed, it was most likely from an ancient East African wild-animal reservoir of plague that the disease broke out to infect so much of the late antique world. ~ Page 18