Ashura is a highly important day for both sects of Islam - the Shias and the Sunnis. The Shia muslims believe that Husayn ibn Ali, the grandson of the Islamic prophet Muhammad, became a martyr at the Battle of Karbala on the tenth day of Muharram in 680 AD.
The gory battle of Karbala was fought for the cause of truth and justice.
The inhabitants on the banks of rivers Euphrates and Tigris were traditional rivals. Their animosity was contained to some extent by Muhammad. But when his son-in-law Hazrat Ali was the Caliph, the old enmity re-surfaced.