Ali Illahism (Persian: علیاللّهی) is a syncretic religion which has been practiced in parts of Iranian Luristan, Pakistan, and India which combines elements of Shia Islam with older religions. It centers on the belief that there have been successive incarnations of the Deity throughout history, and reserves particular reverence for Ali, the son-in-law of the Islamic prophet Muhammad, who is considered one such incarnation. Various rites have been attributed to them, as to the Yezidis, Ansaris, and all sects whose doctrine is unknown to the surrounding Muslim and Christian population. Observers have described it as an of the customs and rites of several earlier religions, including Zoroastrianism.