The Shiites (or Shi'ites or Shia) is one of two major branches of Islam. A schism in Islam occurred in A.D. 660, almost 30 years after the death of Muhammad. The Sunnis, the largest group, disagreed with the Shiites over who should take over the caliphate or leadership of the nascent Islamic community. Those supporting the Prophet's son-in-law, Ali, were called the Shi'at Ali or "Party of Ali" from which the name originates. The Shiite branch of Islam split further into three sub-branches: Zaidi, Ismai'ili(Sevener), and Imamiyya(Twelver). Shiites believe in a line of succession branching off from Muhammad's grandchildren, Hasan and Husein, and is relevant to the names of the Shiite branches. Shiites comprise about one tenth of all Muslims and are the majority faith in Iran and Iraq.
Following the Iranian Revolution in 1979 and the establishment of the theocracy of Ayatollah Khomeini, Iranian Twelver Shiite Islam became associated with Islamic fundamentalism and violent hostility to the West both politically and culturally. However it must be remembered that al Qaeda and the Taliban are entirely Sunni movements. Much of the inspiration for groups like Al-Qaeda comes from the fiercely fundamentalist Wahhabi sect, predominant in Saudi Arabia, and as hostile to Shiite Islam as it is to Christianity and Judaism. Wahhabi ideology is at violent odds with Shiite doctrine, and is subsequently cited as justification for acts of extremism against Shiites.