During the turn of the first millennium the Shia developed as a distinct sect. The Shia employed more rituals in their religious ceremonies, similar to pagan practices, than Sunnis displayed. The Shia themselves have numerous sub-sects that have arisen over differences about which of Muhammad's blood lines, propagated through the progeny of his wives, produced legitimate heirs to the caliphate.
How Sunni and Shia relate each other
Sunni
Sunni Islam is numerically the largest denomination in Islam, its name deriving from “sunnah,” which means words, actions, or the example of the Prophet Muhammad. In historical terms, Sunni Muslims are those ...