A huge number of Iranian Shiite Muslims have set out on the world’s longest Arba’een pilgrimage walk to the city of Karbala, 62 miles southwest of Baghdad, after a farewell ceremony was held on Friday to mark the beginning of the religious march.

The farewell ceremony of the world’s longest mass pilgrimage walk of Arba’een, the 40th day after the martyrdom anniversary of Imam Hussein – the third Shiite Imam – was held in the northeastern Iranian city of Mashhad.

According to a Farsi report by the Azad News Agency (ANA), the ceremony was attended by a number of the province’s people and officials.

Arba’een marks the end of a 40-day mourning period following the day of Ashura, Muharram 10, 61 AH (October 10, 680 AD), on which Imam Hussein as well as his 72 companions sacrificed their lives for the sake of Islam in the Battle of Karbala, which took place in the Iraqi city on the same day.

En route to Karbala, the caravan will pass through five Iranian provinces and some 13 cities including Torbat-e Heydarieh, Bajestan (both located in Khorasan Razavi Province), Ferdows and Tabas (both in South Khorasan Province), Khur and Biabanak County, Nain, Shahreza, Varzaneh, Dehaqan (all located in Isfahan Province), Borujen and Lordegan (both in Chaharmahal and Bakhtiari) as well as Izeh and Ahvaz (both in Khuzestan province). It will enter the Iraqi territory from Shalamcheh border checkpoint in western Iran and will arrive at Imam Hussein’s Holy Shrine on Arba’een.

Every year, millions of Shiite Muslims take part in Arba’een pilgrimage walk, one of the biggest marches worldwide. This year, Arba’een will fall on November 9.