Iranian police chief says some 2.65 million people traveled from Iran to Iraq for Arbaeen pilgrimage.

Arbaeen is a longstanding tradition in Islam, which marks the fortieth day after the martyrdom anniversary of Imam Hussein, the grandson of Prophet Mohammad. Days ahead of the occasion, people in Tehran have gathered en masse to commemorate Imam Hussein.

Iran allows passenger travel through borders to Iraq as flights are restored after a brief halt.

The march is part of a weeklong procession to commemorate the martyrdom anniversary of Imam Moussa al-Kadhim.

A photo exhibition on the Arbaeen pilgrimage has kicked off in Rome, showcasing the largest peaceful gathering in the world.

Tears were shed and prayers held in London's marble arch on Sunday bringing the sights and sounds of Karbala to thousands that gathered there from all over the UK.

Videos and images posted on social media showed bodies lying on the ground in Abuja after police forces open fire on mourners commemorating Arba’een.

Prominent Nigerian cleric, Sheikh Ibrahim Zakzaky, says the 2014 massacre in the northern city of Zaria was a pre-planned crackdown by the government.

Thousands of Muslims in the Indian-controlled Kashmir have marked Arbaeen. 

Mourners across the southern port city flocked to the downtown Karachi to join the main congregation. Miles covered on foot; mourners walked from their neighborhoods all the way to join the main procession before the mausoleum of the founding father Muhammad Ali Jinnah to show their respect for the grandson of Prophet Muhammad.