Millions of people from across the world are converging on the holy Iraqi city of Karbala to take part in mourning rituals on Arba’een, the day which marks 40 days after the martyrdom anniversary of the third Shia Imam, Imam Hussein (PBUH).

Pictures coming out of Iraq show black-clad pilgrims taking part in a march toward Karbala, located about 100 kilometers south of the Iraqi capital of Baghdad, to show their commitment to the Shia Imam with many walking barefoot.

Iraqi forces have tightened security around Imam Hussein’s shrine to protect pilgrims against possible terrorist attacks ahead of the mourning rituals on Thursday.

The northern and western parts of Iraq have been plagued by gruesome violence ever since Daesh terrorists began their campaign of terror in the country in June 2014. Army soldiers and Popular Mobilization units have joined forces and are seeking to take back militant-held regions in joint operations.

Meanwhile, millions of Iranians across the country are also preparing to mark the occasion by holding mourning rituals on Wednesday. Millions of Iranians have also traveled to Iraq to take part in Arba'een march and attend mourning ceremonies in Karbala. 

Imam Hussein and 72 of his loyal companions, including family members, were martyred on Ashura, the tenth day of the lunar month of Muharram, in the battle of Karbala against the second Umayyad caliph, Yazid I, in 680 A.D. Imam Hussein was killed after he refused to pledge allegiance to the tyrant ruler.