Ethiopia (/ˌiːθiˈoʊpiə/; Amharic: ኢትዮጵያ?, ʾĪtyōṗṗyā, ), officially known as the Federal Democratic Republic of Ethiopia (የኢትዮጵያ ፌዴራላዊ ዲሞክራሲያዊ ሪፐብሊክ, yeʾĪtiyoṗṗya Fēdēralawī Dēmokirasīyawī Rīpebilīk ), is a sovereign state located in the Horn of Africa. It shares a border with Eritrea to the north and northeast, Djibouti and Somalia to the east, Sudan and South Sudan to the west, and Kenya to the south. With nearly 100 million inhabitants, Ethiopia is the most populous landlocked country in the world, as well as the second-most populous nation on the African continent after Nigeria. It occupies a total area of 1,100,000 square kilometres (420,000 sq mi), and its capital and largest city is Addis Ababa. Some of the oldest evidence for anatomically modern humans has been found in Ethiopia, which is widely considered the region from which modern humans first set out for the Middle East and places beyond. According to linguists, the first Afroasiatic-speaking populations settled in the Horn region during the ensuing Neolithic era. Tracing its roots to the 2nd millennium BC, Ethiopia was a monarchy for most of its history. During the first centuries AD, the Kingdom of Aksum maintained a unified civilization in the region, followed by the Ethiopian Empire circa 1137. Ethiopia derived prestige with its uniquely successful military resistance during the late 19th-century Scramble for Africa, becoming the only African country to defeat a European colonial power and retain its sovereignty. Subsequently, many African nations adopted the colors of Ethiopia's flag following their independence. It was the first independent African member of the 20th-century League of Nations and the United Nations. In 1974, at the end of Haile Selassie's reign, power fell to a communist military dictatorship known as the Derg, backed by the Soviet Union, until it was defeated by the Ethiopian People's Revolutionary Democratic Front, which has ruled since about the time of the collapse of the Soviet Union in 1991. Ethiopia is a multilingual nation with around 80 ethnolinguistic groups, the four largest of which are the Oromo, Amhara, Somali, and Tigrayans. Most people in the country speak Afroasiatic languages of the Cushitic or Semitic branches. Additionally, Omotic languages are spoken by ethnic minority groups inhabiting the southern regions. Nilo-Saharan languages are also spoken by the nation's Nilotic ethnic minorities. Ethiopia is the place of origin for the coffee bean which originated from the place called Kefa (which was one of the 14 provinces in the old Ethiopian administration). It is a land of natural contrasts, with its vast fertile West, jungles, and numerous rivers, and the world's hottest settlement of Dallol in its north. The Ethiopian Highlands are Africa's largest continuous mountain ranges, and Sof Omar Caves contain Africa's largest cave. Ethiopia has the most UNESCO World Heritage Sites in Africa. Ethiopia's ancient Ge'ez script, also known as Ethiopic, is one of the oldest alphabets still in use in the world. The Ethiopian calendar, which is approximately seven years and three months behind the Gregorian calendar, co-exists alongside the Borana calendar. A slight majority of the population adheres to Christianity (mainly the Ethiopian Orthodox Tewahedo Church and P'ent'ay), while around a third follows Islam (primarily Sunni Islam). The country is the site of the Migration to Abyssinia and the oldest Muslim settlement in Africa at Negash. A substantial population of Ethiopian Jews, known as Bete Israel, resided in Ethiopia until the 1980s, but most of them have since gradually emigrated to Israel. Ethiopia is one of the founding members of the UN, the Group of 24 (G-24), the Non-Aligned Movement, G-77 and the Organisation of African Unity. Ethiopia's capital city Addis Ababa serves as the headquarters of the African Union, the Pan African Chamber of Commerce and Industry, the United Nations Economic Commission for Africa, African Aviation Training HQ, the African Standby Force, and much of the global NGOs focused on Africa. In the 70's and 80's, Ethiopia suffered from civil wars and communist purges which devastated its economy. The country has begun to recover recently however, and now has the largest economy (by GDP) in East Africa and Central Africa. According to Global Fire Power, Ethiopia has the 42nd most powerful military in the world, and the third most powerful in Africa.