Lovers of Imam Hussein (AS) are flocking to Karbala to mark the Arbaeen ritual. So far, more than two million Iranians have crossed into Iraq and more is expected in the next few days.  Karbala is home to the shrine of Imam Hussein, who was martyred along with 72 of his relatives and companions in the battle of Karbala against the forces of the Caliph, in 680 AD.