During the 14th and 15th centuries there were many clashes with the Abyssinians. The Abyssinian raids increased in the 16th century but were finally checked by the armies of the Sultanate of Adel.
The famous Arab leader and warrior of Harrar, the Imam Ahmed ibn El Ghazi, carried his armies right across the Rift Valley up to the Abyssinian plains. Islamic and Arabic traditions spread throughout the region up until the appearance of the first European colonisers in 1854