The Islam religion was founded by Mohammed in the seventh century. In 622 he founded the first Islamic state, a theocracy in Medina, a city in western Saudi Arabia located north of Mecca. There are two branches of the religion he founded.
The Sunni branch believes that the first four caliphs–Mohammed’s successors–rightfully took his place as the leaders of Muslims. They recognize the heirs of the four caliphs as legitimate religious leaders. These heirs ruled continuously in the Arab world until the break-up of the Ottoman Empire following the end of the First World War.
Shiites, in contrast, believe that only the heirs of the fourth caliph, Ali, are the legitimate successors of Mohammed. In 931 the Twelfth Imam disappeared. This was a seminal event in the history of Shiite Muslims. According to R. Scott Appleby, a professor of history at the University of Notre Dame,”Shiite Muslims, who are concentrated in Iran, Iraq, and Lebanon, [believe they] had suffered the loss of divinely guided political leadership” at the time of the Imam’s disappearance. Not”until the ascendancy of Ayatollah Ruhollah Khomeini in 1978″ did they believe that they had once again begun to live under the authority of a legitimate religious figure.
Another difference between Sunnis and Shiites has to do with the Mahdi, “the rightly-guided one” whose role is to bring a just global caliphate into being. As historian Timothy Furnish has written,”The major difference is that for Shi`is he has already been here, and will return from hiding; for Sunnis he has yet to emerge into history: a comeback v. a coming out, if you will.”