Shiites Muslims in Iraq began to celebrate their most important holiday of Ashura in Baghdad on Saturday, one day after five attacks targeting them left at least 30 dead.

The following are some key facts about Ashura.

-- Ashura is dedicated to the mourning of Imam Hussein, grandson of Prophet Mohammed, who was killed defending his faith along with his families in 680 AD in Karbala, 110 km south of Baghdad.

-- Ashura, meaning "ten" in Arabic, takes place on the 10th day of Muharam, the first month in the Islamic lunar calender, which falls on Feb. 19 this year.

-- In black robes, millions of Shiite Muslims make their pilgrimage to the holy shrines in Karbala to celebrate Ashura. Some beat their chests, heads and shoulders with swords in memory of martyred Imam Hussein.

-- Mournings, once forbidden under Saddam Hussein's regime, are coming up on a wide scale as the Jan. 30 polls results helped the Shiites swept the lion's share of power, securing 140 seats in the new national assembly (parliament).

-- The interim Iraqi government has announced it will close land borders from Feb. 17-22 to prevent an influx of foreign pilgrims who may turn out targets for insurgents.

-- Last year's commemoration of Ashura was marred by bombings in Baghdad and Karbala that killed some 170 people.