His birth is said to have been providentially concealed by his father, Hasan al-Askari, out of fear of Abbasid persecution as they sought to eliminate an expected child of the eleventh Imam, whom persistent rumors described as a savior.
After the death of his father in 260 AH (873-874 CE), al-Mahdi is believed by the Twelvers to have entered a state of occultation which continues until his rise in the end of time to establish peace and justice on earth.
[3] Contemporary to the tenth Imam, the Abbasid al-Mutawakkil heavily persecuted the Shia,[4][5] partly due to a renewed Zaydi opposition.
[10] Tabatabai suggests that these restrictions were placed on al-Askari because the caliphate had come to know about traditions among the Shia elite, predicting that the eleventh Imam would father the eschatological Mahdi.
[23][13] Thus began a period of about seventy years, later termed the Minor Occultation (al-ghaybat al-sughra, 260-329 AH, 874–941 CE), during which it is believed that four successive agents represented Muhammad al-Mahdi, the Hidden Imam.
[28] The letter, ascribed to Muhammad al-Mahdi, added that the complete occultation would continue until God granted him permission to manifest himself again in a time when the earth would be filled with tyranny.
[18][31] This and the detailed accounts of Majlesi and Tusi describe Narjis as a captured grand-daughter of the Byzantine emperor and a pious woman who learned about her future union with al-Askari in a dream.
[18][34] Possibly the correct account is the one given by al-Mufid (d. 1022 CE),[35] who writes that Narjis was a slave, born and raised in the house of Hakima Khatun, daughter of al-Jawad (the ninth Imam) and paternal aunt of al-Askari.
[39] The earliest account of his birth is given by Ibn Babawayh on the authority of Hakima Khatun, a close relative who was held in high esteem by the tenth and eleventh Imams.
[36] The account describes that the pregnancy of Narjis miraculously had no physical signs, similar to Moses' mother, and that Hakima Khatun was brought in as midwife only when the birth was due.
[43] The Twelver accounts add that, except for a few trusted associates, the existence of al-Mahdi was kept secret since the Abbasids sought to eliminate the son of al-Askari, whom persistent rumors described as a savior.
[18] Amir-Moezzi and Hussain suggest that this was another tactic by al-Askari to hide the birth of his son: in Shia jurisprudence (fiqh), under certain conditions, the mother is the sole inheritor if the deceased is childless.
[17][51] Ja'far repeated his claims to the imamate after the death of al-Askari,[51] which found a following this time in the form of the now-extinct Ja'fariyya[52] and Fathiyya[53] sects.