World 
In the middle of the 19th century France, Italy, Great Britain and Ethiopia competed for prominence on the Horn of Africa and the territory inhabited by Somalis was divided by the above-mentioned nations. In the 1860s France occupied the current territory of Djibouti and called it French Somaliland. The British established a protectorate, British Somaliland, in northern Somalia in the 1880s. The Italians bought the territory of southern Somalia, Italian Somaliland, from the sultan of Zanzibar in 1889 and the Ethiopians seized the area called Ogaden. After the Second World War, Italian Somaliland came under a UN trusteeship, administered by Italy in preparation for self-rule. On 1 July 1960, the Italian and British Somaliland, having gained independence, formed one state, the United Republic of Somalia. From the inception of independence, many of the ethnic Somalis in Ethiopia and Kenya wanted to join the newly formed Somali state and the Somali government supported the concept of self-determination for the people of the Somali-inhabited areas of Ethiopia, Kenya, and French Somaliland (now Djibouti), including the right to be united within a greater Somalia. This stance became particularly contentious with regards to Ogaden and inter-state conflict broke out between Somalia and Ethiopia intermittently in the course of three decades (in 1960, 1964, 1973, 1983 and 1987).
Internally, the multi-party democratic form of governance that was set up at independence was abruptly ended in 1969 with a bloodless military coup. The Supreme Revolutionary Council, under the leadership of General Siad Barre, established a socialist political system under military rule. The Barre regime outlawed the clan system that deeply characterises the Somali society, forged close ties to the Soviet Union and imposed a Somali brand of "scientific socialism". After a 1978 setback on the Ogadeni battlefront, a military faction consisting of officers from the Darod clan (Marjeeten sub-clan) unsuccessfully launched a military coup. In 1979 the military rule was replaced by a presidential one-party rule with Barre at the helm.
In the 1980s, the Barre regime became more and more dominated by the leader's own Marehan clan (in contradiction to its ideology) and increasingly repressive towards other clans. The authoritarianism incited popular discontent and largely clan-based armed resistance started to sprout, marking the beginning of the intra-state conflict which has continued well into the 21st century. For the remainder of the 1980s, these groups waged guerrilla warfare in different parts of the country with the aim of overthrowing the regime. Towards the end of the decade, the main rebel groups coalesced militarily and managed to overthrow the Barre regime on 26 January 1991.
However, in the power vacuum after Barre's fall the various clan-based armed (and highly fractious) militias began to violently compete for government power and thus pushing the intra-state conflict to the degree of state collapse. As the Somali state lost central authority, the north-western region took the chance to self-declare the independent Republic of Somaliland in 1991. At the beginning of the 21st century the Somali intra-state conflict over government persisted, however, with some new forms of resistance (for example with more Islamist undercurrents) and more robust attempts at forging central administrations (like the 2000 Transitional National Government and the 2004 Transitional Federal Government).
The collapse of the Somali state in 1991 spurred, not only conflict between armed groups and the various provisional governments, but also among and within the oft-clan based opposition movements, with the result of a great number of non-state conflicts. Within the context of this struggle for power, one-sided violence was also used by the armed groups.
Somalia provided secondary warring support to WSLF (Western Somali Liberation Front) in the Ethiopian intra-state 1975-1983 conflict over the Ogaden territory.
Since 1946 Somalia has experienced the inter-state, intra-state, non-state and one-sided categories of UCDP violence.