Saudi Arabia said on Tuesday it has invited Iran's foreign minister to visit, hinting at the possibility of a thaw between the Gulf's two biggest, most bitter rivals who are at loggerheads over Syria's civil war.
Here are some details on the ups and downs of Saudi-Iranian relations over the last three decades:
* 1979 - Iranian Revolution
- Saudi Arabia's rulers watch aghast as Shah Mohammed Reza Pahlavi, a fellow dynast, is toppled by Shi'ite Muslim clerics seen in Riyadh as determined to export their Islamic Revolution.
* 1980-1988 Iran-Iraq War
- Iranians fume over Saudi support for Iraq during the 1980-88 Iran-Iraq war, in which Baghdad uses chemical weapons.
* 1987-88 - Mecca
- Relations between Saudi Arabia and Iran are badly strained 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 wounds 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.
* 1997 - Summit
- 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.
* 1999 - Better Times
- King Fahd congratulates 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 winning 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.
* 2003-2012 - Rise In Regional Tensions
- The 2003 U.S.-led invasion that topples Saddam Hussein in Iraq empowers the country's Shi'ite majority and results in a shift in its political alignment towards Iran.
- The 2006 war between Israel and Lebanese militant group Hezbollah, which gets funding from Iran, 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 hardline nationalist successor Mahmoud Ahmadinejad is bent on dominating the Gulf region.
- According to a Wikileaks cable, King Abdullah tells his own diplomats in 2008 that he wants the United States to "cut off the head of the snake".
* 2011 - Arab Spring
- Saudi Arabia looks on in horror as pro-democracy uprisings moved eastward from Tunisia and Egypt to the Gulf. Protests in Bahrain are seen as a red line because of fears the island's Shi'ite majority will take power and ally with Iran.
- Saudi troops help put down Bahraini Shi'ite unrest at the request of Bahrain's Sunni royal family.
- Saudi Arabia accuses some Shi'ites in its Eastern Province of cooperating with a foreign state - meaning Iran - to sow dissension, after clashes between police and Shi'ites.
- 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.
* 2011-present - Syrian war, U.S.-Iran thaw, nuclear talks
- 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 chilly, complicated by the fact that the two back opposing parties in Syria's civil war. Riyadh is a leading supporter of rebels fighting Syrian President Bashar al-Assad, who is a close ally of Tehran.