Estimates vary of the total attending, from highs of 15-17 million to a low of 6-7 million, but it includes at least two million Iranians whose numbers are easier to calculate because they require documentation to enter Iraq.
Mohammed al-Hilli, the author of a book entitled The pilgrims carry black, green, red and white flags, with the black flag of mourning for Imam Hussein by far the most common.
The indie flick has been panned by critics as it currently has a 15% from 48 reviews on review aggregation site Rotten Tomatoes.
The 30-year-old star was removed from a Pinz in Studio City by staff after getting into an altercation with another bowler.
When the Shia-dominated government took power in Iraq in 2005 it was the first time the Shia had held power in any country in the Arab world since the Fatimids in Egypt were overthrown by Saladin in the 12th century.
It is only now that they have started to look comfortable in their new role.
The Syrian army announced today that it has captured the last Isis-held town in Syria, Albu Kamal, its victory coming a few days after Isis was driven from western Iraq.
Arbaeen is the living symbol of the rise of the Iraqi Shia, a highly significant development in the Middle East, but it has happened only recently.