On 31 July 1987, during the Hajj (Arabic for pilgrimage) in Mecca, a clash between Shia pilgrim demonstrators and the Saudi Arabian security forces resulted in the death of more than 400 people.
[3] Iran and Saudi Arabia have been called "bitter regional rivals" on "opposing sides of bloody conflicts in Syria, Yemen, and Iraq".
Serious loss of life at Hajj occurs periodically (in 1990, 1994, 1998, 2001, 2004, 2006, 2015); not surprising in a situation where two million or more pilgrims "all trying to do the same thing in the same place on the same day" while speaking different languages, and are vulnerable to death from suffocation or being physically crushed in the press of the crowd.
[14] In 2015, an estimated 2,400 pilgrims, including more than 400 Iranians, were killed in a stampede, that led to a "war of words" between Iran and Saudi Arabia that reached a "fever pitch".
[12] For years, Iranian pilgrims had tried to stage demonstrations which are known as "Distancing Ourselves from Mushrikīn" (برائت از مشرکين) in the Muslim holy city of Mecca during the hajj.
[16] These demonstrations had their origins in 1971, when Ruhollah Khomeini instructed his Shiite followers to distribute political messages when performing their pilgrimage.
[17] After the revolution, following the principles elaborated by Khomeini, they appealed directly to the Muslim pilgrims of other lands gradually heightening political activity in each the pilgrimage.
[16] In 1981, this was escalated to chanting political slogans in the Masjid al-Haram and the Prophet's Mosque, two of the holiest sites in Islam, resulting in violent clashes with Saudi security and one death.
[8][20] During the next few years, both sides tried to calm the situation: Khomeini urged his devotees to maintain peace and order, not to distribute printed political material, and not to criticize Muslim governments.
[24][citation needed][25] Internationally, U.S. naval forces were being introduced into the Persian Gulf during this time in response to the Iran-Iraq War and heightening political tensions.
He demanded that the Saudi regime allow Iranian pilgrims to enter the Great Mosque in Mecca at the end of their demonstration,[8] without the presence of security guards.
[3] The march was uneventful until the end of the planned route when the demonstrators found their way blocked by Saudi riot police and National Guardsmen.
In a Washington news conference, the Saudi ambassador Prince Bandar bin Sultan claimed that "not one bullet was fired", blaming the violence on the Iranian pilgrims who he accused of "brandishing knives, clubs and broken glass drawn from beneath their cloaks".
"[11] Ami Ayalon, an Israeli politician, wrote that "most of the Iranian pilgrims apparently shot by Saudi security authorities during the demonstration".
[3] In Iraq, the Revolutionary Command Council, ostensibly an organ of the secular Baath Arab socialist party, demanded that visiting of Islam's holy sites by Iranians should be banned.
[39] Following the incident, Saudi Arabia ended its diplomatic relations with Iran and it reduced the number of permitted Iranian pilgrims to 45,000, down from 150,000 in earlier years.
But no evidence has been produced by Saudi Arabia or Iran to establish that the other side acted deliberately or with premeditation in order to provoke violence.