Most of the peoples of Eritrea and Ethiopia—and some of those in Tanzania and Kenya—speak languages belonging to the Cushitic branch of the Afro-Asiatic languages.
Aromatic gums, tortoiseshell, ivory, and slaves were traded in return.
Arab traders from about 700 seem to have preferred the East African coast to the south of modern Somalia.
The Eastern, or Great, Rift Valley extends from the Red Sea’s junction with the Gulf of Aden southward across the highlands of Ethiopia and Kenya and continues on into Tanzania.
The Western Rift Valley curves along the western borders of Uganda and Tanzania.
For discussion of the physical and human geography of individual countries in the region and of their late colonial and postcolonial history, describes in some detail the shore of what was to become northern Somalia.