Running for 1,608 kilometers, the Iran–Iraq border is Iran’s longest border with a neighboring country. It begins in the south in Khuzestan Province and, passing through marshlands, plains, and mountainous areas, extends northward to West Azerbaijan Province.

In the past, a border did not exist as a defined line. At that time, the vast area separating the two empires was called a frontier, meaning the furthest extent of an empire’s advance into surrounding regions. Gradually, the term “border region” replaced the notion of the frontier.⁠[1]

Iran’s total borders with neighboring countries amount to 8,574 kilometers, of which 3,965 kilometers are land borders, 2,045 kilometers are river, lake, and marsh borders, and 2,565 kilometers are maritime borders. Iran has a total of 45 kilometers river, lake, and marsh borders with Armenia; 756.8 kilometers with Azerbaijan (178.7 kilometers land border and 587.1 kilometers river border); 1,189.9 kilometers with Turkmenistan (403.9 kilometers shared maritime border and 786 kilometers land border); 566.1 kilometers with Turkey (524.2 kilometers land border and 41.9 kilometers water border); and 919.1 kilometers with Afghanistan (237.7 kilometers water border and 681.4 kilometers land border). Its longest border is with Iraq, extending 1,608 kilometers.⁠[2]

The Iran–Iraq border line begins in the south from the thalweg line of the Arvand River in Khuzestan Province and continues to the ridgeline of Dalanper-e Bozorg Mountain, the location of the tripoint boundary marker of Iran, Iraq, and Turkey in West Azerbaijan Province. Of the total border distance between the two countries, about 600 kilometers—from Dalanper-e Bozorg Mountain to the Qasr-e Shirin plain—consists of highlands and mountainous regions, where the border line generally follows the ridgelines. About 300 kilometers of the border strip—from the Qasr‑e Shirin plain in Kermanshah Province to the Mehran plain in Ilam Province—pass through eroded mountains and peaks. From the Mehran plain to the areas where the branches of the Karkheh River enter the border regions west of Bostan in Khuzestan Province, the border extends 400 kilometers across flat and hilly terrain. From that point to the Khin River, where the Shatt al-Arab (Arvand) forms the shared border, the border runs for 220 kilometers through marshlands. The remaining 84 kilometers of the border—from this point to the mouth of the Arvand River on the Persian Gulf coast—run along the Arvand River.⁠[3] The Iran–Iraq border is marked by 125 main boundary pillars and more than 574 subsidiary markers.⁠[4]

Among the most important rivers forming the shared border with Iraq are Zab-e Kouchak (45 kilometers) in West Azerbaijan Province; Qezeljeh-Su (15 kilometers) in Kurdistan Province; Kangagush (75 kilometers), Alvand (55 kilometers), Qoreh-Tu (34 kilometers), and Zimkan and Sirvan (42 kilometers) in Kermanshah Province; and Changuleh, Talkhab (4 kilometers), Konjan-Cham (205 kilometers), Doveyrej (25 kilometers), and Meymeh (25 kilometers) in Ilam Province.⁠[5]

The Qandil,⁠[6] Suren,⁠[7] Randoleh,⁠[8] and Babuleh⁠[9] mountains are also among the border peaks of the two countries.

Among the oil resources of the two countries, twelve oil fields are jointly located in the border regions of Naftshahr (Somar), Barzegan (the Hamrin border mountains in Iraq across Musian in Iran), and Majnoon (Talaeiyeh), which are jointly used.⁠[10]

Iraq’s main population centers are concentrated in a crescent-shaped belt 100 to 200 kilometers from Iran’s borders; more than 80 percent of Iraq’s population, as well as its economic, service, and cultural facilities and settlements, lie in the eastern half of the country close to Iran’s borders.⁠[11] More than 12 million Iranians also live in provinces bordering Iraq.⁠[12]

Linguistically, people on both sides of the border speak Persian, Arabic, Kurdish, Turkish, Assyrian, Armenian, Mandaic, and Hebrew, and religiously they include Muslims, Christians, and Jews.

From a socio-cultural perspective, factors such as shared religious affiliations, religious authority,⁠[13] migration across the borders, joint struggle against the Baathist regime,⁠[14] the rise of Shiites to power in Iraq,⁠[15] economic exchange, religious tourism,⁠[16] tribal ties, and intermarriage between residents of the two countries⁠[17] have created deep connections between the people of Iran and Iraq, especially in border areas.

Today, thirteen border markets—Tamarchin, Qasem-Rash, and Oshnavieh in West Azerbaijan Province; Siranband, Bashmaq, and Seif in Kurdistan Province; Shushmi, Sheikh Saleh, Parvizkhan, Tileh-Kuh, and Khowsravi in Kermanshah Province; and Mehran and Dehloran in Ilam Province—operate as official border markets. The crossings of Khowsravi (Kermanshah Province), Mehran (Ilam Province), and Shalamcheh (Khuzestan Province) function as official commercial borders between the two countries,⁠[18] while the border crossings of Bashmaq, Tamarchin, Parvizkhan, Chazabeh, Shalamcheh, Khowsravi, Somar, Shushmi, Sheikh Saleh, Salehabad, Siranband, Kileh, Marivan, and Mehran are active transit points along the border. Twenty-one unofficial crossing points in the northern sector and seventeen in the southern sector of the Iran-Iraq border have also been identified, used for illegal crossings by smugglers and nationals of both countries.⁠[19]

Iran’s border with Iraq has long been a scene of military confrontation between the two countries. Between 1968 and 1974, and up to the conclusion of the Algiers Agreement on June 13, 1975, more than 100 military clashes were reported along Iran’s border with Iraq.⁠[20]

After the victory of the Islamic Revolution, the Iraqi government attempted to extract concessions from the newly established Islamic Republic by attacking Iran’s borders. From February 1979 to September 1980, border violations by Iraq were recorded as follows: 12 cases in West Azerbaijan Province, 36 in Kurdistan Province, 283 in Kermanshah Province, 195 in Ilam Province, and 278 in Khuzestan Province.⁠[21]

With the outbreak of Iraq’s full-scale war against Iran, Iran’s borders were attacked along three northern, central, and southern fronts.

According to the operational plan of the Baathist army, the fulfillment of the main objective of Iraq’s attack on Iran—the southern front—was assigned to Iraq’s Third Corps. The operational axes envisioned by Iraqi military commanders for a classical army offensive were aligned with the main roads and access routes, which naturally dictated a specific method of attack. A key feature was the use of roads for armored movement and logistical support. Accordingly, Iraq’s Third Corps organized its movement on the southern front along four axes: (a) Tanumeh–Shalamcheh–Khorramshahr; (b) Nashwa–Jofeir–Ahvaz; (c) Amarah–Chazabeh–Bostan–Susangerd; and (d) Fakkeh–Shush–Dezful.⁠[22]

On the central front, the main objective was to capture parts of Iranian territory in order to eliminate any possibility of Iranian advances toward Baghdad and to secure the capital while pursuing the main goals in the south. The axes of Iraq’s offensive on the central front were: (a) Qasr-e Shirin–Sarpole Zahab–Pataq; (b) Mandali–Somar–Naftshahr; and (c) Mehran.⁠[23]

On the northern front, Iraq’s First Corps, with the 7th and 11th divisions, was tasked with protecting the region, controlling Iraqi opponents of Saddam’s regime, and equipping and supporting Iranian anti-revolutionary elements in order to facilitate the separation of Kurdistan and parts of West Azerbaijan.⁠[24]

During Iraq’s invasion of Iran, the country’s airspace was also subjected to air attacks, and economic, military, and residential targets in the cities of Urmia, Tabriz, Piranshahr, Sanandaj, Qasr‑e Shirin, Gilan‑e Gharb, Eslamabad, Kermanshah, Hamedan, Ilam, Tehran, Isfahan, Dehloran, Shahr‑e Kord, Dezful, Ahvaz, Abadan, Khorramshahr, and Bushehr were struck by Iraqi Air Force aircraft.⁠[25]

As Iranians began defending against the invasion, and up until June 1982, a total of 11,200 square kilometers of border areas were liberated, while 1,300 square kilometers remained under enemy control.⁠[26]

After the recapture of Khorramshahr on May 24, 1982, and the adoption of a strategy of pursuing the aggressor, Iranian forces crossed the border into Iraq and liberated significant portions of Iraqi territory. From late June 1982 to August 1988, 1,250 square kilometers of Iranian land and 1,565 square kilometers of Iraqi territory were liberated.⁠[27]

After Iran accepted UN Security Council Resolution 598, Iraq once again launched large‑scale attacks along the northern, central, and southern fronts of the border, achieving some initial gains during the first three days. However, resistance by Iranian military and popular forces changed the situation, and on July 25, 1988, Iraq officially announced its withdrawal.⁠[28] Subsequently, United Nations observer forces were deployed along the Iran-Iraq border, and a formal ceasefire between the two countries took effect on August 20, 1988.⁠[29]