Modern relations between the two nations turned increasingly negative following the 14 July Revolution in Iraq in 1958, and subsequent overthrow of the Hashemite Monarchy which resulted in the country withdrawing from the Baghdad Pact.

[2] Increasing influence of Tehran in Iraqi politics has led to civilians protesting the foreign involvement and presence of Iran-backed militias harassing and attacking citizens.

On 7 September 2018, Iraqi citizens set the Iranian embassy on fire as a part of a series of protests and arson against the foreign power seen as becoming too influential in local domestic politics.

It controlled the cities of Isin, Larsa and Eshnunna, and extended from the Mediterranean (north Syrian) coast to the Persian Gulf and Western Iran.

In 647 BC, the Assyrian king Ashurbanipal leveled the Elamite capital city of Susa during a war in which the inhabitants apparently participated on an opposing side.

A tablet unearthed in 1854 by Austen Henry Layard in Nineveh reveals Ashurbanipal as an "avenger", seeking retribution for the humiliations the Elamites had inflicted on the Mesopotamians over the centuries.

After the defeat of the Cimmerians and Scythians, all of Nebuchadrezzar's expeditions were directed westwards, although a powerful neighbour lay to the North; the cause of this was that a wise political marriage with Amytis of Babylon, the daughter of the Median king, had ensured a lasting peace between the two empires.

Of the four residences of the Achaemenids named by Herodotus—Ecbatana, Pasargadae or Persepolis, Susa and Babylon—the last [situated in Iraq] was maintained as their most important capital, the fixed winter quarters, the central office of bureaucracy, exchanged only in the heat of summer for some cool spot in the highlands.

With the exception of the Roman occupation under Trajan (A.D. 98–117) and Septimius Severus (A.D. 193–211), the Arsacids ruled until a new force of native Iranian rulers, the Persian Sassanids, conquered the region in A.D. 227.

During the reign of its first seven caliphs, Baghdad became a center of power where Arab and Iranian cultures mingled to produce a blaze of philosophical, scientific, and literary glory.

[citation needed] Since the Ottoman–Persian Wars of the 16th and 17th centuries, Iran (known as "Persia" prior to 1935) and the Ottomans fought over Iraq (then known as Mesopotamia) and full control of the Shatt al-Arab until the signing of the Treaty of Zuhab in 1639 which established the final borders between the two countries.

[18]: 4  The Shatt al-Arab was considered an important channel for both states' oil exports, and in 1937, Iran and the newly independent Iraq signed a treaty to settle the dispute.

[19] The 1937 treaty recognised the Iran–Iraq border to be along the low-water mark on the Shatt al-Arab's eastern side, except at Abadan and Khorramshahr, where the frontier ran along the thalweg (deepest part of the river valley).

On 18 December 1959, Iraq's new leader, General Abd al-Karim Qasim, declared: "We do not wish to refer to the history of Arab tribes residing in al-Ahwaz and Mohammareh [Khorramshahr].

Iraq began supporting secessionist movements in Khuzestan, and raised the issue of its territorial claims at an Arab League meeting, though unsuccessfully.

At the same time, by the late 1960s, the build-up of Iranian power under Shah Mohammad Reza Pahlavi, who had gone on a military spending spree, led Iran to take a more assertive stance in the region.

[19] The Shah justified his move by arguing that almost all river borders around the world ran along the thalweg, and by claiming that because most of the ships that used the waterway were Iranian, the 1937 treaty was unfair to Iran.

[19] (Joint Operation Arvand) Iran's abrogation of the treaty marked the beginning of a period of acute Iraqi-Iranian tension that was to last until the 1975 Algiers Agreement.

"[21] Soon, Iraqi radio stations began exclusively broadcasting into "Arabistan", encouraging Arabs living in Iran and even Baloch people to revolt against the Shah's government.

In 1971, Iraq (now under Saddam's effective rule) broke diplomatic relations with Iran after claiming sovereignty rights over the islands of Abu Musa, Greater and Lesser Tunbs in the Persian Gulf following the withdrawal of the British.

[25]: 298  The British journalist Patrick Brogan wrote that "the Iraqis celebrated their victory in the usual manner, by executing as many of the rebels as they could lay their hands on.

When informed of this plot, Saddam ordered the execution of dozens of his army's officers and in a sign of reconciliation, expelled Ruhollah Khomeini, an exiled leader of clerical opposition to the Shah, from Iraq.

The Shah, in turn, attempted to organize a coup against Saddam Hussein in 1971 and helped Sultan Qaboos of Oman quell an Iraqi-backed rebellion.

Although Iran condemned the Iraqi invasion of Kuwait, the former enemies reestablished diplomatic relations in October 1990; one month later, Iranian Foreign Minister Ali Akbar Velayati visited Baghdad.

The high-level meeting by the justice ministers of both countries in Tehran followed in the aftermath of a raid by Iraqi forces on Camp Ashraf, home of the People's Mujahedin of Iran (MEK).

[33] Iran has taken an increasingly salient role within the Iraqi government and security forces since the United States originally withdrew and ISIS rose to power.

[4] On 9 April 2019, a day after the United States placed Iran's IRGC in the list of "Foreign Terrorist Organizations", Iraqi Prime Minister Adel Abdel Mahdi said he had talked to all sides and tried to stop the designation.

[39] On June 26, 2022, Iraqi Prime Minister Mustafa Al-Kadhimi said in Tehran, a day after traveling to Saudi Arabia in an effort to resurrect negotiations between the regional adversaries to end years of antagonism, that Iran and Iraq had agreed to work toward Middle East stability.

[42] Each month, more than 40,000 Iranians visit Shiite holy sites such as Najaf and Karbala, buying religious souvenirs and supporting the economy through tourism.

Iraq imports cars, construction materials, medicine, fruits, spices, fish, air conditioners, office furniture, carpets and apparel from Iran.