Karbala is a city in central Iraq and one of the most important holy cities in Shia Islam. The citys religious significance derives from the Battle of Karbala, a one-sided contest in which al-Husayn ibn Ali, the Shiʿi leader and grandson of the Prophet Muhammad, and his small party were massacred by a much larger force sent by the Umayyad caliph Yazīd I. The battle is commemorated during an annual ten-day period during the Islamic month of Muharram by Shia, culminating on the tenth day of the month, known as the Day of Ashura. Al-Husayns tomb, located in the city, is one of the most important Shiʿi shrines and centers of pilgrimage, including the annual Arbaʿeen pilgrimage 40 days after the commemoration of Ḥusayn’s death. The citys religious community has maintained close ties with coreligionists in Iran, and a significant portion of Karbalas population is of Iranian descent. Karbala still functions as a trade center and a departure point for the pilgrimage to Mecca.