Somalia, officially the Federal Republic of Somalia, is a country in the Horn of Africa. It is bordered by Ethiopia to the west, Djibouti to the Northwest, the Gulf of Aden to the north, the Indian Ocean to the east, and Kenya to the southwest. Somalia has the longest coastline on Africa's mainland. Its terrain consists mainly of plateaus, plains, and highlands. Hot conditions prevail year-round, with periodic monsoon winds and irregular rainfall. Somalia has an estimated population of around 15 million and has been described as Africa's most culturally homogeneous country. Around 85% of its residents are ethnic Somalis, who have historically inhabited the country's north. Ethnic minorities are largely concentrated in the south. The official languages of Somalia are Somali and Arabic. Most people in the country are Muslims, the majority of them Sunni. In antiquity, Somalia was an important commercial center. It is among the most probable locations of the fabled ancient Land of Punt. During the Middle Ages, several powerful Somali empires dominated the regional trade, including the Ajuran Sultanate, the Adal Sultanate, and the Sultanate of the Geledi. In the late 19th century, the Somali Sultanates were colonized by Italy, Britain and Ethiopia. European colonists merged tribal territories into two colonies, but in Somaliland, Sayid Mohamed's Dervish movement managed to frustrate the Abyssinians, Italians and British during expeditions against Somaliland four times, forcing them to retreat to the coast, before finally being defeated in the 1920 Somaliland Campaign. Italy acquired full control of the northeastern, central, and southern parts of the area after successfully waging the Campaign of the Sultanates against the ruling Majeerteen Sultanate and Sultanate of Hobyo. In 1960, the two territories united to form the independent Somali Republic under a civilian government.