After the overthrow of Saddam foreign fighters entered Iraq from other countries such as Syria to join the fight against American forces. Much violence took place in the Sunni Triangle, an area between the cities of Baghdad, Fallujah, and Tikrit. On 20 March 2003, American and British forces began the attack on Iraq. By 9 April 2003, Baghdad-and Saddam's regime-had fallen. Predominant Ethno-religious groups were Kurd, Sunni, Shiite, Kurd Sunni mix, and Shiite Sunni mix. Kurds were in the northeast of Iraq. West Iraq regions were sparsely populated.

After the overthrow of Saddam foreign fighters entered Iraq from other countries such as Syria to join the fight against American forces. Much violence took place in the Sunni Triangle, an area between the cities of Baghdad, Fallujah, and Tikrit. On 20 March 2003, American and British forces began the attack on Iraq. By 9 April 2003, Baghdad-and Saddam's regime-had fallen. Predominant Ethno-religious groups were Kurd, Sunni, Shiite, Kurd Sunni mix, and Shiite Sunni mix. Kurds were in the northeast of Iraq. West Iraq regions were sparsely populated.