Horn of Africa covered the Simien and Bale Mountains but melted at the beginning of the Holocene. The mountains descend in a huge escarpment to the Red Sea and more steadily to the Indian Ocean. Socotra is a small island in the Indian Ocean off the coast of Somalia. Its size is 3,600 km (1,390 sq mi) and it is a territory of Yemen. The lowlands of the Horn are generally arid in spite of their proximity to the equator. This is because the winds of the tropical monsoons that give seasonal rains to the Sahel and the Sudan blow from the west.
Languages of Africa expansion, in which Bantu-speaking peoples expanded over most of Sub-Equatorial Africa, displacing Khoi-San speaking peoples from much of Southeast Africa and Southern Africa and other peoples from Central Africa. Another example is the Arab expansion in the 7th century, which led to the extension of Arabic from its homeland in Asia, into much of North Africa and the Horn of Africa. Trade languages are another age-old phenomenon in the African linguistic landscape. Cultural and linguistic innovations spread along trade routes and languages of peoples dominant in trade developed into languages of wider communication (lingua franca). Of particular importance in this