The earliest Imamite scholar to give an account of the Twelfth Imam's mother is al-Mas'udi. He reports that she was a slave-girl called Narjis [ithbat, 248. For the later authors who named her as Narjis see al-Irshad, 390; T. al-Ghayba, 153, 158; ‘Uyun, 32-3.]. Al-Shahid (d. 786/1384) states that her name was Maryam b. Zayd al-`Alawiyya [bihar, LI, 28, quoted from al-Dirus.], and other reports give her name as Rayhana, Saqil and Sawsan.ss It is possible that her name was in fact Narjis and the other names, except Saqil, were given to her by her owner Hakima bint Muhammad al-Jawad. People at that time used to call their slave-girls by different names as a form of flattery, and Narjis, Rayhana and Sawsan are all names of flowers. The earliest report concerning the nationality of the Twelfth Imam's mother goes back to the year 286/899. This was written down for the first time by al-Saduq, on the authority of Muhammad b. Bahr al-Shaybani, who attributed his narration to Bishr b. Sulayman al-Nakhkhas. According to this report she was a Christian from Byzantium who had been captured by Islamic troops[Kama’l, 431-2]. She was sold as a slave and bought by al-Nakhkhas in the slave-market in Baghdad. Al-Nakhkhas sent her to the tenth Imam, `Ali al-Hadi, in Samarra. After this, however, the narration begins` to lose much of its credibility and becomes hagiographical. It is related that she was Malika b. Yashshu', the granddaughter of the Emperor of Byzantium, whose mother was a descendant of Simon (Sham' un) the disciple of Jesus. When Malika was in her grandfather's palace, she dreamt that she saw Jesus's mother, Mary, and Muhammad's daughter, Fatima. In this dream Fattima converts her to Islam and persuades her to allow herself to be captured by Islamic troops [Kama’l, 317-23.]. The authenticity of this narration is questionable in many aspects, the most doubtful points being found in the last part. Firstly there was no major battle between the `Abbasids and the Byzantines after 242/856 [Tabari, III, 1434] and there is no indication in the sources that the Emperor of Byzantium appealed to the `Abbasids to liberate his granddaughter. Secondly, the early Imamite authors, particularly al-Qummi, al-Nawbakhti, al-Kulayni and al-Mas'udi, who were contemporaries of al-Shaybani, the narrator of this report, do not refer to it in their works. In addition, al-Kashshi, who was a companion of al-Shaybani, and the later scholars al-Najashi and Ibn Dawud claim that he was an extremist [ikhtiyar, 147-8; al-Najashi, 298; Ibn Dawud, al-Rijal, 541]. Thirdly, al-Kulayni states that al-Qa’im's mother was a slave-girl from al-Nawba, the northern province of Sudan [al-Kafi, I, 323]. Moreover al-Nu'mani and al-Saduq related other narrations which indicate that al-Qa’im's mother was to be a black slave-girl [N. al-Ghayba, 84, 85, 120; Kama’l, 329]. It may be that the later Imamites ignored these transmissions and considered the narration of al-Shaybani as authentic because the latter makes al-Qa’im’s mother of noble ancestry and high social status. They would have been particulary attracted by the connection the report establishes between the Twelfth Imam, al-Qa’im, and Jesus, since prophetic traditions state that the two of them will rise together to rid the world of tyranny [Kama’l, 280, 345; al-Marwazi, Kitab al-Fitan, Mss fol, 150-63.]. In the light of these three points the narration of-Muhammad b. Bahr al-Shaybani can be rejected despite the fact that al-Tusi and Ibn Rustam al-Tabari consider it reliable [T. al-Ghayba, 134-9; Dala'il, 262-4]. Possibly the correct account of the origin of al-Qa’im's mother is given by al-Mufid, who states that she was a slave-girl brought up in the house of Hakima, the sister of the tenth Imam. According to his report the Imam saw her one day and predicted that she would give birth to someone with special Divine blessing [al-Irshad, 390-1]. According to al-Saduq she died before the death of her husband, al-Hasari al-`Askari, in 260/874.[Kama’l, 431] But al-Najashi's report indicates that she was alive after this year hiding at the house of Muhammad b. `Ali b. Hamza, one of the close associates of her husband al-`Askari [al-Najashi, 268]. Source: http://www.al-islam.org/occultation_12imam/6.htm#10