The Islamic Courts Union was a group of Sharia courts that united themselves to form a rival administration to the Transitional Federal Government (TFG) of Somalia, with Sharif Sheikh Ahmed as their head. They were also known as the Joint Islamic Courts, Union of Islamic Courts (UIC), Supreme Islamic Courts Council (SICC). or the Supreme Council of Islamic Courts (SCIC). Western media often refer to the group as Somali Islamists.
Until the end of 2006, they controlled most of southern Somalia and the vast majority of its population, including most major cities such as Jowhar, Kismayo, Beledweyne, and the capital Mogadishu. The ICU was supported by warlord Yusuf "Indho Ade" Mohamed Siad who ruled Lower Shabelle but later became defense chief of the ICU, who aided in the defeat of the Mogadishu warlords. Only the Northern regions (Puntland, Somaliland), and the furthest interior regions of the south were outside their control. In December 2006, the ICU lost much territory after defeats at the battles of Baidoa, Bandiradley, and Beledweyne, retreating to the capital, Mogadishu. On December 28 they abandoned Mogadishu, leaving the city in chaos while they moved south towards Kismayo, which allowed the TFG and Ethiopian troops to take over the city. After a stand at the Battle of Jilib, the ICU abandoned the city of Kismayo on January 1, 2007. Stripped of almost all their territory, it was speculated the ICU would pursue guerrilla-style warfare against the government.
Instead, hardline Islamists broke ranks from the ICU and formed other militant groups, such as Al-Shabaab and Hizbul Islam, to continue the war against the government.
The less-militant members of the ICU went into exile in Eritrea and Djibouti, where they formed the Alliance for the Re-Liberation of Somalia in September 2007. In the two years following the ICU's ouster from Mogadishu, the hardline Islamist groups concentrated their power in the south and west of Somalia, taking ground from both the TFG and ICU.
By January 2009, a reconciliation and powersharing deal was brokered between the Transitional Federal Government (TFG) and the Djibouti contingent from the former Islamic Courts Union which resulted in the expansion of the Parliament and the election of Sheik Sharif Ahmed, former leader of the ICU, as President of the Transitional Federal Government.