[citation needed] The two countries are also major trade partners and are perceived as mutually interdependent due to geographical proximity (Iran–Turkey border) as well as historically shared cultural, linguistic, and ethnic traits.

In ancient times, the Asia Minor formed one of the core regions of the Achaemenid Empire, with the cities of Sardis and Smyrna in western Anatolia being the most notable.

Iğdır Province, in what is now Eastern Anatolia, formed part of Qajar Iran up to the outcome of the Russo-Persian War (1826–1828) and the ratified Treaty of Turkmenchay.

Between 16 June and 2 July 1934, Reza Shah Pahlavi visited Turkey with several high-ranking officials, including General Hasan Arfa (at the invitation of Mustafa Kemal Atatürk).

In August 1955, the Central Treaty Organization (CENTO), a mutual security pact between Iran, Turkey, Iraq, Pakistan and Britain was established.

In July 1964, the Regional Cooperation for Development (RCD), aimed at joint economic projects between Iran, Turkey and Pakistan, was established.

Today, Iran and Turkey closely cooperate in a wide variety of fields, such as fighting terrorism, drug trafficking, and promoting stability in Iraq and Central Asia.

In May 2010, Turkish Prime Minister Recep Tayyip Erdogan made an unscheduled trip to Tehran in coordination with Brazilian President Lula da Silva to make an agreement to outsource Iranian uranium enrichment to his country to avoid further sanctions on Iran.

[6] Iranian Major General Yahya Rahim Safavi also expressed his opinion over the situation: "the behaviour of Turkish statesmen towards Syria and Iran is wrong and, I believe, they are acting in line with the goals of America," adding that "if Turkey does not distance itself from this unconventional political behaviour it will have both the Turkish people turning away from it domestically and the neighbouring countries of Syria, Iraq and Iran reassessing their political ties.

Iran's relations with Turkey have occasionally soured over the Turkish AKP government's active involvement in regional disputes between Shia and Sunni groups since the dawn of the Arab Spring.

[12][13] During the 2015 military intervention in Yemen, Iran and Turkey supported rival groups (Shia and Sunni, respectively), which led to official arguments between Recep Tayyip Erdoğan and Mohammad Javad Zarif.

[14] Before the ascent of the Islamist AKP government to power in 2002, Turkey (a constitutionally secular state) had maintained a neutral foreign policy with regards to the religious and sectarian conflicts in the region.

[17] Other matters also aggravate relations, such as both countries supporting opposing sides in Yemeni Civil War (2015–present), and Turkey's installation of a NATO radar tracking Iranian activities (Mahmoud Ahmadinejad said that the NATO defense system deployed in southeast Turkey was meant to protect Israel from Iranian missile attacks).

[19] From January 2017 onward, Turkey has collaborated closely with Iran and Russia in the Astana talks to resolve the Syrian Civil War.

[citation needed] Both Turkey and Iran say they want to put a stop to the conflict even though both countries are supporting opposing sides in the Syrian war.

[25] In February 2019, Turkey refused an invitation by the United States to attend a summit in Warsaw on countering Iranian influence in the Middle East, on the grounds that it "targets one country".

[29] Iranian foreign minister Mohammad Javad Zarif has voiced opposition to the offensive, viewing it as a violation of Syria's sovereignty.

[32] According to Ahval News, an analyst wrote that while the two countries are competing for influence in Central Asia, particularly in Muslim republics, it is hindering them from becoming real allies.

[42] Iran also warned of the presence of "terrorists" near its border, referring to the Syrian jihadists which Turkey and Azerbaijan have been accused of using in Nagorno-Karabakh.

Turkey's foreign minister Mevlut Cavusoglu said to Zarif on a phone call that Iran's public statements against the Turkish leader were unacceptable and "baseless".

[49] Additionally, Harakat Hezbollah al-Nujaba, another Iranian proxy, issued a warning that it would attack Turkey if it did not end its operations in Iraq.

[53][54] In the days following the fall of the Assad regime in Syria, Ayatollah Khamenei appeared to blame Turkey, alongside the U.S. and Israel, for the ousting of Bashar al-Assad.

[57] According to NBC News, a member of the Turkish parliament said that the 2011 Syrian uprising led Turkey to agree that they need Iran and Russia in order to stop a Kurdish state from forming on its southern border.

Iranian First Vice President Mohammad-Reza Rahimi announced in October 2012 that the speed of trade exchanges between Iran and Turkey has accelerated and was close to reaching the goal of $30 billion per year.

[citation needed] On April 29, 2019, Turkey and Iran highlighted their intentions of increasing cooperation in the aspect of transportation according to Hurriyet daily news.

[66] On 17 December 2020, the Iranian Customs Administration announced the re-opening of the Bazargan border crossing in the northwest of Iran, which had shut down 3 months earlier due to the COVID-19 crisis.

Despite talks of resuming the pipeline, millions of barrels remain stuck, affecting global oil prices and destabilizing Iraq's economy, particularly the Kurdish region.

The standoff risks regional instability, U.S. investments, and the rise of rival factions, potentially triggering civil conflict in both Iraqi Kurdistan and wider Iraq.