For various reasons, the twelfth Imam, Imam Mahdi (PBUH) from the first day of his life, did not appear publicly, and for about seventy years people were in communication with him through the intermediary of his special representatives, in order of succession: Othman Ibn Sa’id, Muhammad Ibn Othman, Hussain Ibn Ruh, and Ali Ibn Muhammad al-Samari. This period of seventy years is known as the minor occultation (Al-Ghaybat Al-Sughra), and at the end of that period the major occultation (Al-Ghaybat Al -Kubra) began. One of the reasons was: he is the last Imam and he should be saved by Allah to return and fill the world with justice to spread the orders of God. On the other hand, enemies of Imams and enemies of God knew him by the prophecies, so they attempted to kill him, but God, made him disappear to save him just like prophet Jesus (PBUH), because their returning is the great promise of God in religions.
