The Saudi Arabian government's Ministry of Hajj has set up a permanent tent city to house Muslim pilgrims in Mina, where the ritual Stoning of the Devil takes place as part of the overall Hajj pilgrimage to Mecca. A tent city is also set up at Mount Arafat, another essential stop during the Hajj. Because up to four million pilgrims may be performing the Hajj annually, the tent cities are densely inhabited with 20-40 people per tent. As such, fire and disease outbreaks were constant concerns. Since the late 1990s, Saudi authorities have started using fireproof tents to reduce the risks of a major fire.