Ethiopia is a landlocked country in the Horn of Africa, formally known as the Federal Democratic Republic of Ethiopia. It is bordered on the north by Eritrea, on the northeast by Djibouti and Somaliland, on the east by Somalia, on the south by Kenya, on the west by South Sudan, and on the northwest by Sudan. Ethiopia is the 13th most populous country in the world and the second most populous in Africa, with a total area of 1,100,000 square kilometers and a population of over 109 million people. Addis Ababa, Ethiopia's capital and largest city, is located several kilometers west of the East African Rift, which divides the country into the African and Somali tectonic plates. Ethiopian national identity is rooted in the traditional and contemporary positions of Christianity and Islam, as well as Ethiopia's independence from foreign rule, which dates back to ancient Ethiopian kingdoms. Ethiopia provides some of the earliest skeletal evidence for anatomically modern humans. It is generally assumed that it was from this area that modern humans first set out for the Middle East and beyond. Linguists believe that the first Afroasiatic-speaking peoples arrived in the Horn during the Neolithic period. Ethiopia's governing structure, which dates back to the second millennium BC, has been a monarchy for the majority of its existence. Oral history claims that the Kingdom of Aksum was established by the Solomonic dynasty of the Queen of Sheba, and that its first king, Menelik I, retained a unified culture in the region in the first centuries. During the late–19th-century Scramble for Africa, Ethiopia and Liberia were the only two countries to avoid long-term colonisation by a European co-op. Ethiopia developed its current boundaries during this period by conquering territory to the east, west, and south. Ethiopia was the first African country to join the League of Nations and the United Nations as an independent nation. Italy annexed the country in 1936, and it became Italian Ethiopia as part of Italian East Africa until 1941, when it was liberated during World War II. During Italian rule, the government abolished slavery, which had been practiced for centuries, and urbanization grew steadily. The Derg, a communist military government supported by the Soviet Union, overthrew Haile Selassie's long-standing Ethiopian monarchy in 1974. The People's Democratic Republic of Ethiopia was founded by the Derg in 1987, but it was overthrown in 1991 by the Ethiopian People's Revolutionary Democratic Front, which has been the dominant political coalition since then. Ethiopia is a multilingual country with about 80 ethnolinguistic groups, with the Oromo, Amhara, Somali, and Tigrayans being the four main. The majority of the population speaks Cushitic or Semitic Afroasiatic languages.