About three million Iranians have registered for the rally on Iran’s SAMAH automation system, a legal process which does away with the need to get an Iraqi visa, Iran’s Central Arbae’een Committee said.
Iranian authorities have predicted that more than three million mourners will take part in this year's rally, topping numbers in previous years.
Thousands of non-Iranian pilgrims have also entered Iran, joining the trek for Karbala.
The foreign pilgrims come mostly from Iran’s neighboring countries, such as Pakistan, Afghanistan, Azerbaijan and Turkey.
This image shows Arba'een pilgrims waving Azerbaijani and Turkish flags on the northern Astara border crossing on October 2019. (Photo by Mehr News Agency)
Earlier this week, Sistan and Baluchistan provincial police chief Brigadier General Mohammad Qanbari said that more than 40,000 pilgrims had entered the country from Pakistan alone.
The reports come as millions from Iraq and around the world travel to the holy Iraqi cities of Najaf and Karbala to attend Arba'een.
The gathering is known to attract about 20 million participants every year. This year’s Arba’een falls on October 19.
The event marks the 40th day after the anniversary of the martyrdom of the third Shia Imam, Hussein ibn Ali (AS).
Imam Hussein (AS) was martyred along with dozens of his companions during a laststand battle against the tyrant of the time, Yazid I, more than thirteen centuries ago.
The martyrdom of Imam Hussein (AS) has turned into a symbol of righteous revolt and social and political reform.
Imam Hussein (AS) is consequently a highly-venerated figure not only
among Shia Muslims but also among Sunnis and people of other faiths.
‘Enemies seeking to sow discord will fail’
This year’s Arba’een pilgrimage takes place as Iraq is recovering from several days of protests against mismanagement and corruption last week.
Some of the demonstrations descended into violence and bloody clashes. Violent protests have receded in the past days, however.
Last week, some Arab media outlets reported a US-backed plan seeking to influence the protests in a bid to create instability and push certain political agendas in the country.
Observers have pointed out that the timing of the provocations signals foreign-backed elements seek to undermine Arba’een processions, specifically through fueling antagonism towards Iran.
On Sunday, Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei tweeted that "Iran and Iraq are two nations whose hearts & souls are tied together through faith in God”.
The Leader said that an enemy plot seeking to “sow discord” between the two nations will fail.
Iraqis take pride in hosting pilgrims participating in Arba'een, many of whom are from Iran.
The event has consequently turned into a symbol of unity between the people of the two countries who deeply venerate Imam Hussein (AS).