50 People in Karbala

That's the number of people who were killed by twin suicide bombs in Karbala, where pilgrims had gathered to commemorate the death of Imam Hussein, the Prophet's nephew and son-in-law, and also neither the first nor the last person to be killed in a massacre of a religious sect in the Holy Land, which has quite a few more holes since the invention of high explosives.  The Christian Science Monitor's Dan Murphy wrote an article comparing the recent surge in attacks to the one four years ago in 2006:
Massive suicide attacks on Shiite pilgrims and places of worship have been a fact of life in Iraq from practically the moment in March 2003 when Saddam's statue was pulled down in Firdos Square in Baghdad. ... In the years after, the steady tattoo of Sunni attacks on Shiites helped tip Iraq into civil war (though they weren't the only reason; Shiites participated in their fair share of score settling against Sunnis in the wake of Saddam's fall). In 2006, when a bomb destroyed the Askariya Shrine in Samarra (the third holiest site to Shiites in Iraq after the shrines of Ali and Hussein), Iraq's bloodletting hit new heights of indiscriminate savagery, with reprisal killings and torture commonplace on both sides of the sectarian divide.
But Sunni-Shia violence predates 2004 or even 1984 by centuries.  One ironic reason for this is the effective and thurough religious education system common accross Southwest Asia.  In 1979, writing from post-revolution Iran, Trinidadian writer V.S. Naipaul observed that "to keep alive ancient animosities, to hold on to the idea of personal revenge even after a thousand years, to have a special list of heroes and martyrs and villians, it was necessary to be instructed."  Even way back in 1824, James Morier wrote in The Adventures of Hajji Baba of Ispahan that, in what would later become Iran:
 excepting on the subject of religion, and settling who are worthy of salvation and who to be damned, no one opens his lips.  Every man you meet is either a descendant of the Prophet or a man of the law.
The 50 people who died in Karbla yesterday (and the 60 who were blown up in Tikrit, and the 10 killed north of Baghdad) will have plenty of company in the after life.