And it's because the political and religious coexisted from the beginning that there's no separate tradition of civic and religious law like there is in Christianity and Judaism. So then when Muhammad died in 632 CE, there wasn't a religious vacuum left behind. Muhammad was the final prophet, the revelation of the Quran would continue to guide the ummah throughout their lives. But the community did need a political leader, a caliph, and the first caliph was Abu Bakr, Muhammad's father-in-law, who was not without his opponents. Many people wanted Ali, Muhammad's son-in-law, to lead the community, and although he did become the fourth caliph, that initial disagreement, to radically oversimplify because we only have ten minutes, began the divide between the two major sects of Islam, Sunni and Shia. And even today, Sunni Muslims believe Abu Bakr was rightly elected the first caliph, and Shia Muslims believe it should have been Ali. To Sunnis, the first four caliphs, Abu Bakr, Umar, Uthman, and Ali, are known as the rightly guided caliphs, and many of the conservative movements in the Islamic world today are all about trying to restore the Islamic world to those glory days, which, like most glory days, were not unambiguously glorious.