Around 22 million of Shiite Muslims are travelling to the Iraqi city of Karbala for one of the world’s largest religious events, which is the "Arbaeen," according to Iraqi officials.
They have been walking for days to reach the tomb of Imam Hussein, the grandson of the prophet Muhammed who was killed in Karbala in 680 AD.
Arbaeen in Arabic means "forty" which is the end of the forty days after the anniversary of the death of Hussein in which Shiites beat their heads and chests mourning death of Hussain.
Some of the pilgrims, clad in black clothes, came from distance areas such as Basra which is over 400 kilometers away.
A labourer from Iraq's deep south, Mohammed Hussein Jassem, said "I arrived in Karbala after walking for 12 days."
The road to Karbala is lined with "mawakeb" which are service tents which provide the pilgrims with free food and drinks.
According to Iraqi state TV, five million of the visitors are foreigners of which 4 million are Iranians.
On Monday, the Iraqi Interior Ministry criticised Iran for allowing tens of thousands of Shiite Muslim to cross the Iraqi border without visas.
Last year, at least 17 million people came to Karbala for the "Arbaeen," according to authorities.
Around 30,000 security personnel were deployed for the safety of the people gathering in and around Karbala. But even still, in Baghdad a suicide bomber targeted worshipers on Monday, killing nine people and wounding another 21.
Hashim al-Musawi, a spokesman for the umbrella group of Shiite militias in Iraq called the Popular Mobilization Forces, said that Iranian advisors are ready to cooperate with security forces.
"We have a joint operations room," al Musawi said.
"It enables the Iranian advisers who have expertise in the field of security to help protect the visitors," he added.
The city of Karbala, which has a regular population of around 700,000 people, is located between the Euphrates river and Anbar Province where fierce clashes between DAESH and the PMF have taken place.
DAESH currently controls vast swathes of northern and Western Iraq. Furthermore, fighting is still ongoing in Ramadi between the two sides in Ramadi city, 90 km away from Karbala.