Somalis (Somali: Soomaaliyeed, Arabic: الصوماليون‎) are an ethnic group located in the Horn of Africa, also known as the Somali Peninsula. The overwhelming majority of Somalis speak the Somali language, which is part of the Cushitic branch of the Afro-Asiatic language family. Ethnic Somalis number around 15-17 million and are principally concentrated in Somalia (more than 10 million), Ethiopia (4.6 million), Yemen (a little under 1 million), Kenya (900,000), Djibouti (464,600), and an unknown but large number live in parts of the Middle East, North America and Europe.

Samaale, the oldest common ancestor of several Somali clans, is generally regarded as the source of the ethnonym Somali. The name "Somali" is, in turn, held to be derived from the words soo and maal, which together mean "go and milk" — a reference to the ubiquitous pastoralism of the Somali people. Another plausible etymology proposes that the term Somali is derived from the Arabic for "wealthy" (dhawamaal), again referring to Somali riches in livestock.

An Ancient Chinese document from the 9th century referred to the northern Somali coast — which was then called "Berbera" by Arab geographers in reference to the region's "Berber" (Cushitic) inhabitants — as Po-pa-li. The first clear written reference of the sobriquet Somali, however, dates back to the 15th century. During the wars between the Ifat Sultanate based at Zeila and the Solomonic Dynasty, the Abyssinian Emperor had one of his court officials compose a hymn celebrating a military victory over the Sultan of Ifat's eponymous troops.
Following World War II, Britain retained control of both British Somaliland and Italian Somaliland as protectorates. In 1945, during the Potsdam Conference, the United Nations granted Italy trusteeship of Italian Somaliland, but only under close supervision and on the condition — first proposed by the Somali Youth League (SYL) and other nascent Somalian political organizations, such as Hizbia Digil Mirifle Somali (HDMS) and the Somali National League (SNL) — that Somalia achieve independence within ten years.[49][50] British Somaliland remained a protectorate of Britain until 1960.

To the extent that Italy held the territory by UN mandate, the trusteeship provisions gave the Somalis the opportunity to gain experience in political education and self-government. These were advantages that British Somaliland, which was to be incorporated into the new Somali state, did not have. Although in the 1950s British colonial officials attempted, through various administrative development efforts, to make up for past neglect, the protectorate stagnated. The disparity between the two territories in economic development and political experience would cause serious difficulties when it came time to integrate the two parts. Meanwhile, in 1948, under pressure from their World War II allies and to the dismay of the Somalis, the British "returned" the Haud (an important Somali grazing area that was presumably 'protected' by British treaties with the Somalis in 1884 and 1886) and the Ogaden to Ethiopia, based on a treaty they signed in 1897 in which the British ceded Somali territory to the Ethiopian Emperor Menelik in exchange for his help against plundering by Somali clans.

Aden Abdullah Osman Daar, the first President of Somalia and an early Somali Youth League leader.
Britain included the proviso that the Somali nomads would retain their autonomy, but Ethiopia immediately claimed sovereignty over them. This prompted an unsuccessful bid by Britain in 1956 to buy back the Somali lands it had turned over. Britain also granted administration of the almost exclusively Somali-inhabited Northern Frontier District (NFD) to Kenyan nationalists despite an informal plebiscite demonstrating the overwhelming desire of the region's population to join the newly formed Somali Republic.

Abdirashid Ali Sharmarke, Somalia's first Prime Minister and second President.
A referendum was held in neighboring Djibouti (then known as French Somaliland) in 1958, on the eve of Somalia's independence in 1960, to decide whether or not to join the Somali Republic or to remain with France. The referendum turned out in favour of a continued association with France, largely due to a combined yes vote by the sizable Afar ethnic group and resident Europeans. There was also widespread vote rigging, with the French expelling thousands of Somalis before the referendum reached the polls.[58] The majority of those who voted no were Somalis who were strongly in favour of joining a united Somalia, as had been proposed by Mahmoud Harbi, Vice President of the Government Council. Harbi was killed in a plane crash two years later. Djibouti finally gained its independence from France in 1977, and Hassan Gouled Aptidon, a Somali who had campaigned for a yes vote in the referendum of 1958, eventually wound up as Djibouti's first president (1977–1991).

British Somaliland became independent on June 26, 1960 as the State of Somaliland, and the Trust Territory of Somalia (the former Italian Somaliland) followed suit five days later. On July 1, 1960, the two territories united to form the Somali Republic, albeit within boundaries drawn up by Italy and Britain. A government was formed by Abdullahi Issa and other members of the trusteeship and protectorate governments, with Haji Bashir Ismail Yusuf as President of the Somali National Assembly, Aden Abdullah Osman Daar as the President of the Somali Republic and Abdirashid Ali Shermarke as Prime Minister (later to become President from 1967–1969). On July 20, 1961 and through a popular referendum, the people of Somalia ratified a new constitution, which was first drafted in 1960. In 1967, Muhammad Haji Ibrahim Egal became Prime Minister, a position to which he was appointed by Shermarke. Egal would later become the President of the autonomous Somaliland region in northwestern Somalia.

Lieutenant Colonel Salaad Gabeyre Kediye, the "Father of the Revolution" initiated by the Supreme Revolutionary Council.
On October 15, 1969, while paying a visit to the northern town of Las Anod, Somalia's then President Abdirashid Ali Shermarke was shot dead by one of his own bodyguards. His assassination was quickly followed by a military coup d'état on October 21, 1969 (the day after his funeral), in which the Somali Army seized power without encountering armed opposition — essentially a bloodless takeover. The putsch was spearheaded by Major General Mohamed Siad Barre, who at the time commanded the army.[63]

Alongside Barre, the Supreme Revolutionary Council (SRC) that assumed power after President Sharmarke's assassination was led by Lieutenant Colonel Salaad Gabeyre Kediye and Chief of Police Jama Korshel. The SRC subsequently renamed the country the Somali Democratic Republic, dissolved the parliament and the Supreme Court, and suspended the constitution.

The revolutionary army established large-scale public works programs and successfully implemented an urban and rural literacy campaign, which helped dramatically increase the literacy rate. In addition to a nationalization program of industry and land, the new regime's foreign policy placed an emphasis on Somalia's traditional and religious links with the Arab world, eventually joining the Arab League (AL) in 1974. That same year, Barre also served as chairman of the Organization of African Unity (OAU), the predecessor of the African Union (AU).