Crowds of worshippers have already begun to gather in Makkah in the days ahead of Haj.
“It’s the first time I’ve felt something so strongly — it’s striking,” said 40-year-old Indonesian pilgrim Sobar in rudimentary Arabic.
More than 1.8 million visitors had arrived by midday local time on Tuesday, authorities said.
Crowds of faithful from across the world wore flowing white robes as they descended on the holy city located in the west of Saudi Arabia.
“Islam united us. We are all together… so that’s why I’m very happy,” said Leku Abibu, 46, a Ugandan mechanic who wore a beige Shalwar Kameez.
This year’s Haj takes place amid tensions in the Gulf region exacerbated by a series of attacks on oil tankers, drone strikes and interception of maritime traffic on the high seas.
Saudi Arabia and its ally Washington accuse Iran of being behind the attacks and sabotage operations against commercial shipping.
Tehran has denied responsibility.
Despite the absence of diplomatic ties between Saudi Arabia and Iran, some 88,550 Iranian pilgrims are due to take part in Haj this year, according to the Tasnim news agency.
‘No differences between us’
Haj is one of the five pillars of Islam and Muslims must perform it at least once in their lives if they can afford to.
“There are all nations of the world, all languages. There are no differences between us,” said Nurul Jamal, a 61-year-old pilgrim from India.
Masjid al Haram, or The Great Mosque, with its Ottoman minarets sits amid skyscrapers that host upmarket malls and luxury hotels.
Pilgrims circle the holy Kaaba seven times and perform a number of sacred rites.
While waiting for the beginning of Haj, worshippers pray in the esplanade or inside the mosque amid stifling heat.