NAJAF, Iraq — This year's pilgrimage of Arbaeen is different from previous years, as it now bears new political connotations in light of the developments in Iraq and the region. Arbaeen is a Shiite religious ceremony that commemorates the martyrdom of Hussein ibn Ali, the grandson of the Prophet Muhammad. Forty days after Ashoura, Shiites take part in a long procession that travels from different Iraqi cities to the holy city of Karbala, where Hussein was buried.

Iraqi Shiites have observed this ritual for hundreds of years under the different political regimes that have ruled Iraq. The ritual became a cultural celebration observed by a large number of Iraqi Shiites. In recent years, Shiites from other countries started to participate in this gathering.

Saddam Hussein's regime cracked down on Arbaeen and banned related gatherings for three decades, resulting in Shiite outrage in central and southern Iraq. At the first Arbaeen gathering after the fall of Saddam in 2003, about 2 million Shiite pilgrims marched to Iraq's south. Arbaeen crowds have grown with each subsequent year, with 20 million participating in 2014.

The regional situation has contributed greatly to the increase in Arbaeen pilgrims, whose gathering now bears messages between the conflicting forces. The ritual is no longer a purely cultural ceremony but has become something of a political protest. It's a show of force against those hostile to the rise of the Shiites in the region.