More than 20 million Shia Muslim pilgrims have converged on the Iraqi shrine city of Karbala (a holy city in central Iraq, central to Shia Islam) for the Arbaeen festival, one of the largest religious gatherings in the world. The event marks the end of the 40-day mourning period following the martyrdom of Imam Hussein, a central figure in Shia tradition. The scale of this year's pilgrimage is particularly notable given the ongoing wars and instability across the broader Middle East region.