Resumen: The historical interaction between Islam and Christianity in the Horn of Africa is profoundly connected with the region¿s specifi c historical, linguistic and cultural characteristics. While the western coast of Africa faces the vastness of the Atlantic Ocean, since antiquity the northern part of Africa¿s eastern coast as far as the Bab al-Mandab has interacted with the Red Sea and the Arabian Peninsula. The Arab geographers called all the various populations living on the western coast of the Bab al-Mandab `Habash¿, while Abyssinia is the ancient name of the northern parts of modern Ethiopia, corresponding to modern Tigray and Eritrea. In recent scholarship, the term `Greater Ethiopia¿ has been used to refer to Ethiopia in its twentieth-century borders before the independence of Eritrea in 1993.