Page "History of Eritrea" Paragraph 21

With the rise of Islam in the 7th century the power of Aksum declined and the Kingdom became isolated, the Dahlak archipelago, northern and western Eritrea, came under increasing control of Islamic powers based in Yemen and Beja lands in Sudan. The Beja were often in alliance with the Umayyads of Arabia who themselves established footholds along stretches of the Eritrean coastline and the Dahlak archipelago while the Funj of Sudan exacted tribute from the adjacent western lowlands of Eritrea.