It is worth mentioning that the most important aspect of the Ismailism, which deserves serious treatment is to keep everything secret under the garb of taqiya connected with their faith, tending their enemies to contrived baseless stories and myths against them. The veiled period (dawr-i satr) thus became benigh climate for them to cultivate different wrong genealogies of the Imams. Thus, the ancestry of the Fatimids has confounded the students of history due to divergent accounts given by the historians, which had been developed round the persons of the "hidden Imams" (aima'i masturin) during concealment period. The widespread Abbasid propaganda, the derogatory attitude of Sunnite and Shiite authors make difficult to decide one way or the other about the legitimacy of their claim. In the light of the Fatimid policy, we are inclined to believe that the Fatimids deliberately seem to have avoided discussing the matter of their ancestry. It emerges from this a safe conclusion that it was a preconceived plan of the Fatimids to keep their genealogy a top secret, owing to the intricate and dark passages it passed through and due to contradictions involved in the adoption of assumed names by the hidden Imams.
The variety of lineages suggested by the writers amounted to several hundreds, and the lineage between Wafi Ahmad and Radi Abdullah alone has been altered in no less than fifty ways. Since the hidden Imams had assumed different names in various regions to outsiders, in order to evade the vigilance of the Abbasids, the historians derived their informations on hearsay. The Ismaili Imams of that period were too cautious to disclose their true names; instead they assumed names, other than their owns and used for themselves the names of their dais. The hidden Imams, for the most part, could not pass the settled lives in specific places, but were known by names other than their own, sometimes by names of their dais and hujjats as a precautionary measure designed to ward off the danger of their persons being discovered.
The absence of detailed biographies of the three hidden Imams is also the result of their having lived in strict disguise. This seems quite probable, if one realizes the situation very seriously. What in fact would the popular memory preserve about the Imams when these were living ostensibly as local merchants, carrying on their business, associating with friends, directing their followers through secret agency of mission, marrying, educating their children, etc. The memory of these traditions is very meagre, retaining only reminiscences of the most important names and events. Similarly, the Ismaili dais also disguised as pious merchants of slightly lower standing, also left behind very trivial traces. Thus the leaving of any trace of their activities in writing was obviously avoided as much as possible. W.Ivanow writes in "The Rise of the Fatimids" (Calcutta, 1942, pp. 43-44) that, "Thus the long blank period in the story of the Imams, living in such conditions, cannot reasonably be taken as valid proof of the falsity of their claims to continuous succession from their original ancestor, Ismail b. Jafar."
Even though the period of concealment and fear of the Abbasids were no longer in existence, the Fatimids were insistent not to divulge the names of their earlier three hidden Imams, the link between Imam al-Mahdi and Imam Muhammad bin Ismail. It seems quite possible that these Imams had assumed names for more than one time, and hid their true names, and were too complicated to be clarified. The followers also seem to have given much priority on the Imam of the time, descending from Muhammad bin Ismail. This secrecy however led too much confusion and made it too hard to locate the real names of the hidden Imams. It is also a striking feature that these three hidden Imams are not mentioned by the early renowned Ismaili scholars, viz. Abu Hatim ar-Razi (d. 322/934), Qadi Noman (d. 363/974), Jafar bin Mansur al-Yamen (d. 365/975) and other authors of 4th/10th century.
Commenting the aggressive attitude of the historians, Ivanow writes in "The Rise of the Fatimids" (Calcutta, 1942, p. 29) that, "With their predominantly hostile tendency, each author vie with the others in inventing something more humiliating and scandalous for the dynasty." The diversity of the names of the three hidden Imams can be judged from the following list of some special surname and epithet, whose implications were intelligible only to the trusted followers, indicating a causative factor of the contradictions in the sources:
ABDULLAH : Radi, Ahmad, Abu Muhammad, al-Wafi AHMAD : Wafi, Muhammad, Abul Hussain, at-Taqi. HUSSAIN : Muhammad, Taqi, Ahmad, Abu Abdullah, az-Zaki, al-Muqtada al-Hadi, ar-Radi.
The fact about the Imams assuming the above code names in one or more times can be derived from the letter of Imam al-Muizz (341-365/953-975), which he routed in 354/965 to his dai in Sind, named Jaylam bin Shayban, which is preserved in the 5th volume of "Uyun'l-Akhbar" by Idris Imaduddin. According to "Expose de la Religion des Druzes" (Paris, 1838, p. 252) by de Sacy, "These men (hidden Imams) obliged to seek concealment, took sometimes one name and sometimes another, in order to shelter from the pursuit of their enemies." John Nicholson also writes in "Establishment of the Fatemide Dynasty in Northern Africa" (1840, p. 12) that, "They themselves have taken different names at different times in order to elude discovery."
According to "an-Naqdu'l-Khafi" by Hamza (cf. "Expose de la Religion des Druzes" by Silverstre de Sacy, Paris, 1838, p. 74) that the Fatimid Caliph, al-Muizz had once said: "I am the seventh in the second heptad." As is well known, al-Muizz was the 14th Imam in the second heptad. The Imams of the first heptad were seven and the seventh one was Muhammad bin Ismail, and the Imams followed after him were also seven to make al-Muizz as the 14th Imam. Hence, the 13th Imam was al-Mansur, the 12th was al-Qaim and 11th was al-Mahdi. It therefore emerges conclusively that there must have been three Imams between al-Mahdi and Muhammad bin Ismail, whose names were Abdullah (Wafi Ahmad), Ahmad (Taqi Muhammad) and Hussain (Radi Abdullah) from 8th to 10th in the sequence. W. Ivanow writes in "Ismailis and Qarmatians" (JBBRAS, Bombay, 1940, p. 74) that, "Being the fourth Fatimid Caliph, al-Muizz was the seventh Imam after Muhammad bin Ismail. Thus this formally rejects the theory of the Fatimids descending from Abdullah bin Maymun."
The statement of al-Muizz however does not contain the explicit names of the "three hidden Imams", but before that, it is known that al-Mahdi had sent a letter in Yamen, which reached there after his arrival in Mahdiya in 308/921. Jafar bin Mansur al-Yamen (d. 365/975) had quoted the letter in his "al-Fara'id wa Hudud ad-Din" (pp. 13-19), wherein the names of the three hidden Imams have been mentioned, viz. Abdullah, Ahmad and Muhammad. Dr. Sami Nasib Makarem writes in "The Hidden Imams of the Ismailis" (al-Abhath, 21, 1969, p. 24) in this context that, "If al-Mahdi's letter is authentic, it is one of the oldest documents that have come to light until now, and, consequently a most reliable document, especially because it was written by the Caliph al-Mahdi himself."
Among the later Ismaili historians, Ahmad bin Muhammad an-Naysaburi, the author of "Istitaru'l-Imam", compiled under Imam al-Aziz (365-386/975-996) seems first to have mentioned the names of the three hidden Imams. Later on, such references appear in the works of Hamiduddin Kirmani (d. 408/1017), in his "Tanbihu'l-Hadi wa'l-Mustahdi" and "ar-Risalat al-Wa'iza". Idris Imaduddin (d. 872/1468) in "Uyun'l-Akhbar" and Hasan bin Nuh Broachi (d. 939/1533) in "Kitabu'l Azhar", had also advanced brief biographies of the three hidden Imams.
In sum, R. Strothmann writes in "Gnosis-Texte der Ismailiten" (Gottingen, 1943, p. 59) that, "The three Imams followed by Muhammad bin Ismail were in concealment: Abdullah al-Rida, Ahmad al-Wafi and Hussain al-Taqi, and finally the beginning of the Fatimid dynasty with al-Mahdi."