The black flag of Muharram is hoisted at the holy shrine of Hazrat Masoumeh as the mourning month of Muharram begins. Shias mark the martyrdom anniversary of Imam Hussein (AS), the third Shia Imam and grandson of Prophet Mohammad (PBUH) who, together with 72 of his companions, was martyred in the Battle of Karbala back in 680 AD in fight against the tyrant ruler of the time Yazid ibn Muawiyah.