That is total BS.. The Sunni are the descendants of the original inhabitants of the Tigris Euphrates Valley, their recorded tribal and family ancestry dates back past the time of the prophets to Adam, most often Sunni Mosques are built and maintained by a single extended family. The Shia are every one else, the Sunni are often indisposed to handle the manual chores, so they have been bringing in workers from other places for centuries, these workers attend to their religious affairs in Mosques that are in working class areas of the city. At no time has war or conflict between the two sectors of society been permitted either under secular law or within the strictures of Islam, all parties are aware that murder is met with speedy and deadly retaliation according to the instruction in The Koran. Both Sunnis and Shia say the bombings are a plot to incite sectarian violence at the behest of John Negroponte, US Deputy Secretary of State!