Shia Muslims have begun marking Tasu’a, the eve of the martyrdom of Imam Hussein (PBUH), by holding mourning rituals the world over.

The occasion falls on the ninth day on the lunar month of Muharram. It is marked annually by the Shia faithful in honor of the Third Shia Imam and his 72 companions, who were all martyred in the Battle of Karbala by the army of the tyrant of the time, the Umayyad caliph, Yazid I, in 680 AD.

The annual rituals attract millions of Shias in various countries each year, who throng religious centers to perform commemoration rituals. In Iran, people also distribute Nazri (votive food offerings) among other people.

Wearing black as a sign of mourning, people usually gather around religious eulogists, beating their chests to their tunes and shedding tears in memory of the suffering imposed on the Imam, his family, and followers.

Tasu’a is also known as the Day of Loyalty and Resistance, which is devoted to Abbas ibn Ali, Imam Hussein’s half-brother, in deference to his sacrifices in the Battle of Karbala.

That historical battle has come to signify the determined struggle of good against evil and resonates strongly with Shia Muslims.

Millions have, meanwhile, traveled to the holy Iraqi cities of Najaf and Karbala, the latter of which houses Imam Hussein’s shrine, to observe the rituals there.

Mourners mark Tasu’a in Iran, September 30, 2017.

The overall events also represent a symbol of unity among Shias worldwide, and are, hence, known to be sending a message to those seeking to divide them.