Territory of the Kurdistan Region

Under the Iraqi–Kurdish Autonomy Agreement of 1970, the governorates of Erbil, Sulaymaniyah, and Duhok were recognized as majority-Kurdish, and it was planned to establish an autonomous Kurdish region in these areas.^[6] As a result, these three governorates are typically considered the core of the Kurdistan Region today. The agreement also called for a census to be conducted in other governorates, with the possibility of incorporating them into the autonomous Kurdish region.^[1]

However, the autonomy agreement was never fully implemented, and subsequent political and military developments over the following decades altered the territories effectively governed by Kurdish authorities.^[1]

Following the 1991 uprising, Kurdish forces expelled the Iraqi Army from many Kurdish-majority areas. After retreating, the Iraqi Army unilaterally established an ad hoc political boundary known as the Green Line. This line separated Iraqi-controlled territory to the west from Kurdish-controlled territory to the east, encompassing most of the current governorates of Duhok and Sulaymaniyah, all of Halabja, roughly two-thirds of Erbil except for Makhmur District, the northern tip of Diyala Governorate including Kifri, and northeastern parts of Nineveh Governorate including Akre and Lalish, but almost none of Kirkuk governorate. These territories were governed by the Kurdistan Regional Government, which functioned as de facto state in these areas, and the situation remained relatively stable until the 2003 invasion of Iraq.^[3][7][8][9]

Following the 2003 invasion, Article 53.A of Iraq's 2004 Transitional Administrative Law recognized "the territories that were administered by that government [the Kurdistan Regional Government, or KRG] on 19 March 2003 (one day before the invasion) in the governorates of Duhok, Erbil, Sulaymaniyah, Kirkuk, Diyala Governorate, and Nineveh Governorate" as the boundary of the Kurdistan Region, corresponding to the Kurdish-administered areas east of the Green Line. This provision was later incorporated into Article 143 of the 2005 permanent Iraqi Constitution, establishing the Green Line as the official and constitutional boundary between the Kurdistan Region and the rest of federal Iraq, which remains in effect today. However, no authoritative rendering of the Green Line exists.^[3]

On 20 March 2003, following the US-led invasion of Iraq, Kurdish forces, primarily the Peshmerga, advanced across the Green Line, at times with support from US special forces and air operations, and established control over areas they considered Kurdish or historically linked to Kurdish populations, including Kirkuk, Sinjar, Tuz Khurmatu, Khanaqin, Jalawla, Daquq, Makhmour, Bartella, and Bashiqa, among other areas.^[3][9][10] In these territories west of the Green Line, Kurdish forces established a new boundary, known as the Trigger Line.^[11]

Kurdish control of the areas east of the Trigger Line, which were still officially administered by the Iraqi government, remained firm until 2008 as the Iraqi Army was disbanded and Iraqi state institutions deteriorated. The Peshmerga and Asayish provided security, while KRG administrative structures gradually offered public services and controversially, from 2007 onward, the KRG began awarding contracts to international oil companies for exploration blocks that appeared to extend beyond the Green Line.^[3]