Sunni Triangle in the context of "Iraqi Sunni Arabs"

Samarra (Arabic: سَامَرَّاء, Sāmarrāʾ) is a city in Iraq. It stands on the east bank of the Tigris in the Saladin Governorate, 125 kilometers (78 mi) north of Baghdad. The modern city of Samarra was founded in 836 by the Abbasid caliph al-Mu'tasim as a new administrative capital and military base. In 2003 the city had an estimated population of 348,700. During the Iraqi Civil War (2006–08), Samarra was in the "Sunni Triangle" of resistance.

The archeological site of Samarra still retains much of the historic city's original plan, architecture and artistic relics. In 2007, UNESCO designated it a World Heritage Site.

Fallujah (Arabic: ٱلْفَلُّوجَة al-Fallūjah [el.fɐl.ˈluː.dʒɐ]) is a city in Al Anbar Governorate, Iraq. Situated on the Euphrates River, it is located roughly 69 kilometres (43 mi) to the west of the capital city of Baghdad and 50 kilometres (31 mi) from the neighboring city of Ramadi. The city is located in the region defined as Sunni Triangle by the United States, as the majority of its residents are Sunni Arabs. In 1947, Fallujah was a small town with a relatively small population but had grown to a population of about 250,900 people by 2018.

Following the 2003 invasion of Iraq, which triggered the Iraq War, the city became a major centre of resistance during insurgency. The United States, the United Kingdom, and the Iraqi Interim Government twice engaged in fierce urban combat with insurgents throughout the city; the first battle of Fallujah failed to dislodge the insurgents, triggering the second battle, in which the coalition forces successfully took control of the city. However, heavy fighting from these two battles left the city severely damaged, though it remained occupied by the coalition until 2011. In January 2014, three years after the American withdrawal from Iraq, Fallujah was captured by the Islamic State (IS) and suffered a major population decline. On 23 May 2016, the government announced the beginning of a large-scale military offensive against the IS militants occupying the city, resulting in the Third Battle of Fallujah. On 26 June 2016, the Iraqi Armed Forces stated that Fallujah had been fully liberated and was free from militant control.

The Saladin, Salah ad Din, or Salah Al-Din Governorate (Arabic: محافظة صلاح الدين, Muḥāfaẓat Ṣalāḥ al-Dīn) is one of Iraq's 19 governorates, north of Baghdad. It has an area of 24,363 square kilometres (9,407 sq mi), with an estimated population of 1,042,200 people in 2003. It is made up of 8 districts, with the capital being Tikrit. Before 1976 the governorate was part of Baghdad Governorate.

The governorate is named after Saladin or Salah ad-Din. This governorate is largely Sunni Arab and is also where Saddam Hussein, former president of Iraq, was born, in the village of Al-Awja. Salah Al-Din governorate, a traditional stronghold of Saddam and his Al-Bu Nasir tribe that is located in the heart of the Sunni Triangle, has been a centre of insurgencies, tribal rivalries, and political and sectarian violence since the 2003 U.S.-led Coalition invasion of Iraq.

Ramadi (Arabic: ٱلرَّمَادِي Ar-Ramādī; IPA: [r.ra.maː.diː]; also formerly rendered as Rumadiyah or Rumadiya) is a city in central Iraq, about 110 kilometers (68 mi) west of Baghdad and 50 kilometers (31 mi) west of Fallujah. It is the capital and largest city of Al Anbar Governorate which shares borders with Syria, Jordan, and Saudi Arabia. The city extends along the Euphrates which bisects Al Anbar. Founded in 1879, it was one of the towns established during the later period of Ottoman Iraq. By 2018 it had about 223,500 residents, near all of whom Sunni Arabs from the Dulaim tribal confederation. It lies in the Sunni Triangle of western Iraq.

Ramadi occupies a highly strategic site on the Euphrates and the road west into Syria and Jordan. This has made it a hub for trade and traffic, from which the city gained significant prosperity. Its position has meant that it has been fought over several times, during the two World Wars and again during the Iraq War and Iraqi insurgency. It was heavily damaged during the Iraq War, when it was a major focus for the insurgency against occupying United States forces. Following the withdrawal of US forces from Iraq in 2011, the city was contested by the Iraqi government and the extremist group Islamic State of Iraq and the Levant (ISIL) and fell to ISIL in May 2015. On 28 December 2015, the Iraqi government declared, confirming media testimonies, that it had re-taken Ramadi, that government's first major military victory since its loss.