Short answers, pulled from the story.
Italian Somaliland lasted from the late 19th century until 1941, when British troops occupied it during the East African campaign of the Second World War. It was revived from 1950 to 1960 as the Trust Territory of Somaliland under Italian administration.
The northern Somali territories were ruled by the Sultanate of Hobyo and the Majeerteen Sultanate before Italy established protectorate treaties with them in 1889. Sultan Yusuf Ali Kenadid signed for Hobyo on the 8th of February 1889, and Boqor Osman Mahamuud signed for the Majeerteen Sultanate on the 7th of April 1889.
Britain ceded the Jubaland region to Italian Somaliland in 1925 as a reward for Italy joining the Allied side in the First World War. Britain kept the southern half of the old territory, later known as the Northern Frontier District.
The Dervish movement, led by Mohammed Abdullah Hassan, was a leading force in Somali resistance against Italian rule, alongside the Bimaal and Wa'daan clans in the south. Dervish fighters won the Battle of Hiraan in March 1913 and held the region until the campaign of the sultanates in the 1920s.
Italian Somaliland ended in 1941, when British forces occupied the territory during the East African campaign of the Second World War. Italy briefly regained administration from 1950 to 1960 as a United Nations trusteeship before Somalia became independent.
On the 1st of July 1960, the Trust Territory of Somaliland united with the former British Somaliland to form the Somali Republic, with Mogadishu as its capital. That date is still marked as Somalia's Independence Day.