Every year, millions of Muslims converge on the Saudi holy cities of Mecca and Medina for the annual hajj pilgrimage, with the massive ceremonies representing a major security and logistical challenge for the kingdom's authorities.
On occasion, the hajj and events surrounding it have been marred by disasters, such as Thursday’s stampede near Mecca:
2015: In the lead-up to hajj, 111 people are killed and nearly 400 injured when a crane collapses in bad weather, crashing on to the Grand Mosque in Mecca, Islam's holiest site.
2006: More than 360 pilgrims are killed in a stampede at the desert plain of Mina, near Mecca, where pilgrims carry out a symbolic stoning of the devil by throwing pebbles against three stone walls. The day before the hajj began, an eight-storey building being used as a hostel near the Grand Mosque in Mecca collapsed, killing at least 73 people.
2004: A crush of pilgrims at Mina kills 244 pilgrims and injures hundreds on the final day of the hajj ceremonies.
2001: A stampede at Mina during the final day of the pilgrimage ceremonies kills 35 hajj pilgrims.
1998: About 180 pilgrims are trampled to death in panic after several of them fell off an overpass during the final stoning ritual at Mina.
1997: At least 340 pilgrims are killed in a fire at the tent city of Mina as the blaze was aided by high winds. More than 1,500 were injured.
1994: Some 270 pilgrims are killed in a stampede during the stoning ritual at Mina.
1990: The worst hajj-related tragedy claims the lives of 1,426 pilgrims in a stampede in an overcrowded pedestrian tunnel leading to holy sites in Mecca.