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.
Horn of Africa species total and about 90 species which are found exclusively in the region. Among endemic reptile genera, there are "Haackgreerius", "Haemodracon", "Ditypophis", "Pachycalamus" and "Aeluroglena". Half of these genera are uniquely found on Socotra. Unlike reptiles, amphibians are poorly represented in the region. There are about 100 species of freshwater fish in the Horn of Africa, about 10 of which are endemic. Among the endemic, the cave-dwelling Somali blind barb and the Somali cavefish can be found. It is estimated that about 5,000 species of vascular plants are found in the Horn, about half of which are endemic. Endemism is