Lewis, the polity was governed by local Somali dynasties , who also ruled over the similarly-established Sultanate of Mogadishu in the littoral Benadir region to the south. Mostly mountainous, the region arose through faults resulting from the Rift Valley. Central Intelligence Agency. The Horn of Africa is sometimes shortened to HoA or is quite commonly designated simply the "Horn", while inhabitants are sometimes colloquially referred to as Horn Africans. For centuries, the region's pastoral groups have observed careful rangeland management practices to mitigate the effects of drought, such as avoiding overgrazing or setting aside land only for young or ill animals. The lowlands of the Horn are generally arid in spite of their proximity to the equator. Malo Literature Festival's prize. Somalia has only two permanent rivers, the Jubba and the Shabele , both of which begin in the Ethiopian Highlands.