[3] Afghanistan shares a relatively long history with Iran (called Persia in the West before 1935) and it was part of many Persian Empires such as Achaemenid and Sasanian dynasties.

Mirwais succeeded in defeating the declining Safavids in a succession of battles and declared southern Afghanistan a completely independent country.

[7] According to the Daily Pioneer, because of the ongoing agreement between Iran and Afghanistan, their relationship has yet to be manipulated by any third party and will remain so in the future.

[11] On 19 December 1978, Hafizullah Amin requested 20 million rubles in assistance to expand the AGSA and establish a "military intelligence network for the DRA in Iran, Pakistan, and some Arab countries".

In a phone call between Premier of the Soviet Union Alexei Kosygin and General Secretary of the PDPA, Nur Muhammad Taraki, Taraki claimed that 4,000 Iranian soldiers had entered Herat dressed as civilians asking the Soviets to send soldiers from the Central Asian republics in Afghan uniforms to help them counteract Iranian interference.

[13] In December 1979, the Soviet Union sent around 100,000 troops to the Democratic Republic of Afghanistan to assist the PDPA government against a nationwide mujahideen insurgency.

After the death of Khomeini in 1989, the Iranian government encouraged many of the Shi'a groups to combine and establish the Hezb-e Wahdat, hoping that they would be included in international negotiations.

Between the Soviet Union's withdrawal in February 1989 and the fall from power of president Najibullah in April 1992, Iran supported the PDPA government.

In the words of historian Barnett Rubin, "Iran saw the Soviet-backed Kabul government as the main force blocking the takeover of Afghanistan by Sunni Wahhabi parties backed by these three countries [Pakistan, Saudi Arabia, and the United States].

[15][16] Following the emergence of the Taliban government and their harsh treatment of Afghanistan's minorities, Iran stepped up assistance to the Northern Alliance.

Besides Afghan lawmakers, leaders in the United States and many NATO officials also believe that Iran is meddling in Afghanistan by playing a double game.

[34] A number of Afghans were executed by hanging in public for crimes punishable with death in Iran (murder, rape, smuggling large amount of drugs, and armed robbery), which sparked angry demonstrations in Afghanistan.

"[39] "Currently, the Revolutionary Guards recruit young people for terrorist activities in Afghanistan and try to revive the Hezb-i-Islami Afghanistan led by Gulbadin Hekmatyar and Taliban groups"[40]According to Saudi Arabia, Afghan Senate members certified the existence of documents which affirm that the Taliban collected endorsements from both Iran and Russia.

Fars News Agency reported that Ali Shamkhani, a member of Iran's Supreme National Security Council, had talks with the Afghan Taliban when he was visiting Kabul on 26 December 2018.

[44] After the Taliban re-capture of Kabul in August 2021, Iran says its embassy in Kabul remains open,[45] but it "strongly" condemned the Taliban's Panjshir Offensive, with Iranian Foreign Ministry spokesman Saeed Khatibzadeh describing it as "by no means acceptable in terms of international law and humanitarian law.”[46] The city of Tehran would even officially name a street "Panjshir Alley" in protest.

[47] Iranian strategists were dismayed by the prospect of a strong Taliban government in Afghanistan, recalling the hostilities with the First Islamic Emirate during 1996-2001 and its support of American invasion in 2001.

The Sunni Islamic model of the Taliban is also perceived by the Iranian government as a direct threat to its Khomeinist ideological ambitions.

[51][52] Mahmoud Ahmadinejad, an influential former Iranian President, even accused the United States of leading a "satanic and anti-human plot" to put the Taliban back in power in order to influence "all regional countries" such as Iran and also accused Afghanistan's neighboring country Pakistan, as well as Russia, and China, being co-conspirators who "trampled on [Afghan] people's lives, basic rights, and their right to self-determination to secure their own interests.

"[53] Ali Shamkhani, secretary of Iran's Supreme National Security Council (SNSC), publicly insisted on an "inclusive" Taliban government which represents the restrains from "use of military means" and instead of will fulfill obligations of "dialogue to meet the demands of ethnicities and social groups" among the people in Afghanistan.

[54] In September 2021, commander of the Quds Force Esmail Qaani, said that past sectarian conflicts have shown that the Taliban government was "no friend of Iran".

"[55] The prominent Principlist daily publication in Iran, Kayhan, also referred to the Islamic Emirate of Afghanistan as a member of the Axis of Resistance.

[70] Senior officials from the two countries called for de-escalation after an apparently deadly clash over a river water-sharing dispute,[71] though the local Taliban commander, Abdul Hamid Khorasani, threatened to "conquer" Iran if this continues.

[72] On 26 January 2025, a delegation led by Iran's foreign minister visited Kabul and was welcomed by Amir Khan Muttaqi.

In 2009, Iran was one of the largest investor in Afghanistan, which is mainly in the construction of roads and bridges as well as agriculture and health care.

IRNA quoted Mohammad Qorban Haqju as saying that Iran imported $4 million worth of products like fresh and dried fruits, minerals, precious stones, and spices from the neighboring country.

[74] Afghanistan and Iran have been persuaded to cooperate with each other in reciprocal beneficial ways due to worsening economic conditions, according to The Diplomat.

[77] In late February 2024, the Taliban-led government of Afghanistan announced an investment of $35 million in the Chabahar port in southern Iran.

[78] According to The Diplomat, cooperation between Afghanistan and Iran can provide the Taliban regime with more policy options and reduce its dependence on Pakistan.

With a 1973 treaty between the prime ministers of both nations which Iran was supposed to receive a share of 820 million cubic meters of the river each year, but it again was not ratified.