The month of Muharram is the first Islamic month of the Islamic calender, one of the forbidden months of Muslims, in which the greatest tragedy and oppression in the Prophet's family occurred in the history of the Muslim world.
Ashura is one of the events attracted the most attention of Muslims throughout the history, that in addition to its extensive role and profound social and historical impact, it has become a special cultural event now.
The popularity of this day among Muslims is driven from the event of Ashura in the 61 AH, in view of the fact that the major events of Karbala occurred on the ninth and tenth day of the month of Muharram al-Haram; these two days became more prominent, with the names of Tasu'a ("Ta'sa" in Arabic means "Nine" and "Tasu'a" means "Ninth day"), and Ashura ("Ash" means 10th and Ashura, meaning 10th day).
During these days, Imam Hussein (AS), the third Imam of the Shias and seventy-two persons of his followers were martyred with a thirsty lip in the war with a the forces of Yazid in the event of Karbala.
This mourning is not a normal one, and is the greatest mourning happening in this month.
The official holiday of Tasu'a and Ashura is two days in Iranian calendar.
This general mourning begins by wearing the black clothes and blackening the streets, mosques, Husayniyah, etc., by mourning's flags.
After the Ashura, the mourning continues at different times even until the Safar month.