An estimated 1.5 to 2 million Muslims are on the annual pilgrimage to Mecca known as the Hajj. That’s far fewer than last year, as Saudi authorities seek to keep the ritual isolated both from tensions in other Middle Eastern countries and from a health threat that has killed more than 50 people in the kingdom.
After circling the Kaaba - the holiest spot in Islam - the pilgrims converged on a hilltop where Islam’s Prophet Muhammad called on Muslims to unite some 14 centuries ago.
But with Muslims today locked in conflict in parts of the Middle East, this pilgrim from Syria offered his own plea for unity.
"We evacuated our houses and our children got killed, so I pray to God on this great day to swiftly lift our country's suffering," he said.
Still, the Hajj appeared to begin without major disruptions. Some people might have political grievances, says Scottish terrorism expert Stephen Vertigans via Skype.
“But the vast majority of people going there are going there ostensibly on religious grounds, to come together with other Muslims, to express their faith and to go through the different rituals," said Vertigans.
Even without political tensions, it’s an enormous challenge in crowd control - with past years marred by stampedes and a terrorist takeover in 1979.
This year, a respiratory virus centered in the Gulf kept many pilgrims away. The virus has killed more than 50 people in Saudi Arabia.
The Saudi government also reduced quotas because of expansion work at the Grand Mosque.
But the Saudis will be under pressure to lift the quotas and give as many Muslims as possible the opportunity to go, says Vertigans.
“If they are reducing that opportunity for political grounds rather than health and safety grounds, they would become subjected to huge criticism within Muslim communities and Muslim nation-states," he said.
The Hajj ends with the Eid Al Adha holiday, and Muslims around the world celebrate it with feasts and gift-giving.