Horn of Africa Horn of Africa The Horn of Africa (, , , , ) (shortened to HOA; alternatively Somali Peninsula) is a peninsula in Northeast Africa. It juts hundreds of kilometers into the Arabian Sea and lies along the southern side of the Gulf of Aden. The area is the easternmost projection of the African continent. Referred to in ancient and medieval times as "Land of the Berbers" and "Habesha", the Horn of Africa denotes the region containing the countries of Djibouti, Eritrea, Ethiopia, and Somalia. It covers approximately 2,000,000 km (770,000 sq mi) and is inhabited by roughly 115 million people
Horn of Africa single landmass around 18 million years ago, before the Gulf of Aden rifted and separated the Horn region from the Arabian Peninsula. The Somali Plate is bounded on the west by the East African Rift, which stretches south from the triple junction in the Afar Depression, and an undersea continuation of the rift extending southward offshore. The northern boundary is the Aden Ridge along the coast of Saudi Arabia. The eastern boundary is the Central Indian Ridge, the northern portion of which is also known as the Carlsberg Ridge. The southern boundary is the Southwest Indian Ridge. Extensive glaciers once