A pillar of the Islamic faith, this year’s hajj comes with Saudi authorities striving to protect pilgrims from two deadly viruses, Ebola and the MERS coronavirus.
It is also taking place against the backdrop of widespread revulsion among Muslims towards Islamic State group jihadists.
Saudi Arabia and four other Arab nations have joined Washington in air strikes in Syria against the militants, who have declared a “caliphate “straddling that country and Iraq where they have committed a spate of atrocities.
Authorities say close to 1.4 million believers have come from abroad to follow the 1,400-year-old tradition of Prophet Mohammed, alongside pilgrims from Saudi Arabia.
“It is a beautiful feeling,” said Aziza Yousfy, 60, from Algeria, before leaving Mecca.
Seeing nearby Mina Valley and Mount Arafat “has always been a dream for me”, she said.
Mount Arafat is where Prophet Mohammed gave his final sermon, after leading his followers on the hajj.
Sayed Tajamul Haq, 64, an Indian pilgrim walking with his wife, voiced hope that “God will accept our prayers for forgiveness and mercy”, during an experience he described with a smile as “fantastic.
The Arab News reported that a recent French convert to Islam had driven 7,000 kilometres (4,340 miles) from North Africa to take part in the hajj.
Pilgrims were moving a few kilometres (miles) from Mecca to nearby Mina by bus or on foot on Thursday.
Men wear a seamless two-piece white garment, symbolising a state of purity and emphasising their unity regardless of social status or nationality.
Women also generally wear white, exposing only their faces and hands.
Commandos, helicopters stand by
The passage to Mina marks the official start of the hajj on the eighth day of the Muslim calendar month of Dhul Hijja.
In Mina, they will pray and rest before moving on to Mount Arafat for the climax of the pilgrimage rituals on Friday.
Security has not noticeably increased around the holy sites, but an AFP reporter observed three checkpoints between Jeddah and Mecca, where security officers verify that visitors hold hajj permits.
Officials say they have intensified efforts to stop people attending hajj without authorisation, as part of safety measures for such a large gathering with massive logistical challenges.
The official Saudi Press Agency (SPA) said more than 145,000 unauthorised pilgrims have been turned away.
Eighteen aircraft and Black Hawk helicopters will patrol and be on standby for emergencies including “terrorist attacks”, Arab News reported.
“The aircraft are equipped with thermal cameras and shooting platforms, “the newspaper quoted General Mohammed Eid al-Harbi as saying.
Saudi news channel Al-Ekhbariya has broadcast footage of commandos rappelling from helicopters and performing other exercises to demonstrate their readiness.
Supplementing the 85,000 security and civil defence officers who are reportedly deployed for hajj are thousands of health workers.
While Ebola has hit Africa, most MERS cases worldwide have been in Saudi Arabia itself, home to Islam’s holiest sites.
Pilgrims from Guinea, Liberia and Sierra Leone, the three nations hardest-hit by Ebola which has killed more than 3,000 people in West Africa this year, have not been allowed in for the hajj.
No Ebola cases have yet been found in the desert kingdom.
The health ministry on Wednesday announced the country’s latest MERS victim, a 43-year-old Saudi man who died in Taif, east of Mecca.
But “no infectious cases have been recorded among the pilgrims, including coronavirus (MERS),” said Acting Health Minister Adel Fakieh in a statement carried by SPA.
He added that “the health situation of the pilgrims is reassuring.”