This year, Hoi giao in Iran have returned to the pilgrimage after a period of interruption due to diplomatic issues between Iran and Saudi Arabia.
The Saudi Arabian government has mobilized huge resources in hopes of avoiding a repeat of the 2015 incident that killed nearly 2,300 people, including 464 Irans.
This year's pilgrimage takes place in the context of the diplomatic crisis between the Gulf of Tonkin and Qatar.
In addition, the fight against the terrorist group IS continues in the area. Although the IS has lost much of its control in Iraq and Syria, terrorist attacks still occur in the Middle East and Europe.
Saudi Arabian authorities say security is ready to deal with any event.
According to Saudi Arabian Interior Ministry spokesman Mansour al- Turki, more than 100,000 security personnel are deployed at various locations along the Hajj pilgrimage route.
In a simple outfit, Hoi giao converts gathered at Mecca's Grand Mosque, where there are 7 bell towers. Here, believers perform a 7-time roundabout ceremony around Kaaba - a black rock wrapped in a silk fabric embroidered with Koran verses.
This sacred place is where Hoi giaoans around the world come to pray.
The pilgrims then headed to Mina, 5 km east of Mecca. Here, hundreds of thousands of people will gather before leaving in the early morning of August 31 to climb Arafat Mountain.
tidjani Traore, 53, a consultant from Benin, said he is on his 22nd pilgrimage. "Every time, there are new emotions," he said.
This year, Saudi Arabian authorities have placed fog fans in the Grand Mosque space to prevent heat as pilgrims gathered in large numbers.
Regardless of the weather, many pilgrims patiently sit under shade or under concrete bridges waiting for their turn to pray.
Thousands of pilgrims flock to the Mecca site.
