The King of Persia, so there was kinship between his children and them. Persian - And as for their satisfaction with the children of Fatima, it is because they were accustomed from the time of the Caliphs to believe in the theory of divine delegation and that the Caliphs have a spark from God that passes from father to son. This is contrary to the Arab idea which believes in consultation and the rule of those who can bind and loose in choosing the Caliphate according to interests. Because it is a selective and democratic idea of the Arabs. The idea of the Mahdi did not stop at this limit, but played later many roles. If we say that all Fatimid civilization, Fatimid science, and Fatimid Cairo are an indirect product of the idea of the Mahdi, we would not be far off. The success of the Fatimids was a realization of the spiritual idea of the Mahdi, which made others covet it, and the most covetous people were the Shiites. Over time, hadiths spread that supported the idea of the Mahdi, which indicate that he will rule the entire world, east and west, just as Solomon, peace be upon him, and Dhu al-Qarnayn ruled. And that Jesus, peace be upon him, will descend during the time of the Mahdi, and Jesus will follow him in one prayer, which is the dawn prayer in Jerusalem.