Shia Islam in Iraq (Arabic: الشيعة في العراق) has a history going back to the times of Ali ibn Abi Talib, the first imam of Shia Islam and fourth caliph of Sunni Islam who moved the capital of the early caliphate from Medina to Kufa (or Najaf) two decades after the death of Muhammad. Today, Shia Muslims make up the majority of the Iraqi population. After the U.S.-led invasion in 2003, there has been widespread sectarian violence between Shias and Sunnis in Iraq, which became high-intensity in the wars in 2006–2008 and 2013–2017, which involved the Islamic State terror group.