Iran reopened its embassy in Saudi Arabia's capital, Riyadh, on Tuesday, Saudi media reported, months after the two regional rivals agreed to end years of antagonism under a Chinese-brokered deal.
Protracted rivalry between the Middle East's leading Shia and Sunni Muslim-led powers has fuelled conflicts across the region, including wars in Yemen and Syria.
China's role in the diplomatic breakthrough has shaken up dynamics in the Middle East, where the United States was, for decades, the main mediator, flexing its security and diplomatic muscles.
Saudi rulers watch aghast as Iran's Shah Mohammed Reza Pahlavi, a fellow dynast, is toppled by Shia Muslim clerics, seen in Riyadh as determined to export their Islamic Revolution.
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Iranians fume over Saudi support for Iraq during the 1980-88 Iran-Iraq war, in which Baghdad uses chemical weapons.
Relations between Saudi Arabia and Iran take a big hit in July 1987 when 402 pilgrims, 275 of them Iranian, die during clashes in the Muslim holy city of Mecca. Protesters in Tehran occupy the Saudi embassy and set fire to Kuwait's embassy. A Saudi diplomat dies in Tehran of injuries sustained when he falls out of an embassy window and Riyadh accuses Tehran of delaying his transfer to a hospital in Saudi Arabia. King Fahd severs ties with Iran in 1988. Relations are restored only in 1991.
Saudi Crown Prince Abdullah visits non-Arab Iran for an Islamic summit in December, becoming the highest-ranking Saudi to do so since the Islamic Revolution.
READ: Iran to reopen embassy in Saudi Arabia today
Saudi King Fahd congratulates Iranian President, Mohammad Khatami, on his election victory in 2001, saying it is an endorsement of his reformist policy. Khatami had worked for rapprochement with Riyadh after his first landslide win in 1997. Khatami visits Saudi Arabia, the first such trip since 1979. Better relations are sealed with a security pact in April 2001.
The 2003 US-led invasion that topples Saddam Hussein in Iraq empowers the country's Shia majority and results in a shift in its political alignment towards Iran.
The 2005 assassination of Lebanon's Rafik Al-Hariri, a close Saudi ally, sets the stage for a power struggle in Beirut pitting Iran and its allies, on the one hand, including Syria, against US-allied, Sunni-led Gulf Arab states, on the other. Lebanon falls increasingly under the sway of the heavily armed, Iranian-backed Lebanese group, Hezbollah.
Some 15 years later, an UN-backed court convicts three Hezbollah members in absentia over the Hariri killing. The group denies any role, describing the tribunal as a tool in the hands of its enemies.
The 2006 war between Israel and Hezbollah hardens Saudi suspicions that Tehran is creating new regional alliances threatening Saudi interests.
Iran's disputed nuclear energy programme deepens Saudi fears that Tehran, under Khatami's hard-line nationalist successor, Mahmoud Ahmadinejad, is bent on dominating the Gulf region.
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According to a WikiLeaks cable, Saudi King Abdullah tells his own diplomats in 2008 that he wants the United States to "cut off the head of the snake".
Saudi Arabia looks on in horror as pro-democracy uprisings spread eastward from Tunisia and Egypt to the Gulf. Protests in Bahrain are seen as a red line, because of fears the island's Shia majority will take power and ally with Iran.
Saudi troops help put down Bahraini Shia unrest at the request of Bahrain's Sunni Royal family.
Saudi Arabia accuses some Shias in its Eastern Province of cooperating with a foreign state – meaning Iran – to sow dissent, after clashes between police and Shias.
The United States says it has uncovered an Iranian plot to assassinate the Saudi ambassador to Washington. Riyadh said the evidence was overwhelming and Tehran would pay a price. Iran rejects the report as a fabrication aimed at driving a wedge between Tehran and Saudi Arabia.
Moderate Hassan Rouhani is elected Iranian President in June 2013 and turns Iran's hitherto confrontational foreign policy in a conciliatory direction. Iran strikes an interim deal with big powers in November to limit its nuclear activity. Relations between Iran and most Gulf Arab neighbours improve.
The Saudi-led Gulf Cooperation Council calls in December for good neighbourly relations with Iran, based on "non-interference in internal affairs".
But Iranian-Saudi ties remain icy, with their regional power struggle reflected in the Syrian civil war. Riyadh is a leading supporter of Sunni rebels fighting Syrian President Bashar Al-Assad, who is a close ally of Tehran.
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In 2015, Saudi Arabia intervenes in Yemen at the head of a Western-backed coalition against the Houthi Movement after the Iran-aligned group ousts the internationally recognised government from power in the capital, Sana'a. The war later turns into a years-long military stalemate.
Saudi Arabia executes nearly 50 people, including prominent Shia cleric, Nimr Al-Nimr, on 2 January. Protesters in Tehran storm the Saudi embassy and Shia Iran's top leader, Ayatollah Ali Khamenei, vows "divine vengeance" for Nimr's execution.
Saudi Arabia cuts ties with Iran on 3 January.
Iran accuses Saudi Arabia of air strikes on its embassy in Yemen on 7 January. Saudi officials dismiss the claim as propaganda.
On 29 May, 2016, Iran bans its pilgrims from attending the annual Muslim Haj pilgrimage, blaming Saudi Arabia for "sabotage" and failing to guarantee the safety of pilgrims.
On 14 September, 2019, Saudi Arabia blames Iran for attacks on its oil installations that knocked out half of the Kingdom's supply. Iran denies involvement; Yemen's Iran-aligned Houthi group claims responsibility for the attacks.
On 3 January, 2020, Qassem Soleimani, the Iranian military commander, is killed in a US drone strike in Baghdad.
On 9 April, 2021, Iran and Saudi Arabia hold their first direct talks since the rupture, hosted by Baghdad. Between April 2021 and September 2022, four rounds of talks are held, mostly mediated by Iraq and Oman.
Iran pulls out of the talks on 13 March, 2022, ahead of a planned fifth round, a day after mass executions in Saudi Arabia that activists said included 41 Shia Muslims.
Iran and Saudi Arabia hold a fifth round of talks on 21 April, 2022.
On 19 October, 2022, the top adviser to Iran's Khamenei calls for re-opening of the Saudi and Iranian embassies.
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Chinese President, Xi Jinping, visits Saudi Arabia on 9 December, 2022, and holds talks with Crown Prince, Mohammed bin Salman.
Iranian President, Ebrahim Raisi, visits China on 16 February, 2023, to meet Xi.
On 11 March, 2023, Iran and Saudi Arabia agree to re-establish relations in deal brokered by China.
The Saudi and Iranian foreign ministers meet in China on 6 April, their first formal encounter in more than seven years.
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