Abu Hatim ar-Razi was followed by Abu Abdullah Muhammad bin Ahmad an-Nasafi and Abu Yaqub as-Sijistani staying at Ray. An-Nasafi operated the mission mostly in Khorasan and Bukhara, and gained great success in converting the Sunni ruler, Nasr bin Ahmad, who had given allegiance to Imam al-Mahdi and paid him an annual tribute of 119 thousand dinars. Nasr bin Ahmad also entered into correspondence with al-Qaim in Maghrib.
The renowned poet and intellect, Abu Abdullah bin Jafar bin Muhammad bin Hakim bin Abdur Rahman bin Adam ar-Rudaki ash-Shair as- Samarkandi, known as Rudaki (d. 329/940) also found an opportunity of espousing Ismaili faith in this period. Some historians sought to explain the term Rudaki by saying that he was so called because he could play on rud (harp), which is an erroneous view. The poet himself adopted his pen-name, Rudaki because he hailed from a village in the district of Rudak. He was a court poet of the Samanids, and composed many verses in praise of the Fatimid Imams. In one place, Maruf of Balkh, one of the earliest Samanid poets, says: "I have heard the king of poets, Rudaki as saying, `do not give allegiance to anyone save the Fatimids.'"
The Abbasids took notice of the rapid conversion of the Ismailis in Khorasan, notably Nasr bin Ahmad, and insinuated Nuh bin Nasr (331-343/943-954), the son of Nasr bin Ahmad; against his father and the Ismailis. Nuh bin Nasr dethroned his father and conducted a barbarous massacre of the Ismailis in 331/942, known in the Ismaili history as al-mainat al-uzama (great calamity) in Khorasan and Transoxania. An-Nasafi and his chief associates were also executed in the wild operations at Bukhara in 332/943. For this reason, Nasir Khusaro called him Khwaj-i Shahid and Shaikh al-Shahid. It resulted a setback in Ismaili mission, but was resumed under an-Nasafi's son, Masud, surnamed Dihqan and Abu Yaqub as-Sijistani. An-Nasafi is considered a leading Ismaili philosopher among the early Ismailis. He produced a major work, entitled "Kitab al-Mahsul" (Book of the Yield). Paul E. Walker writes in "Abu Yaqub al-Sijistani: Intellectual Missionary" (London, 1996, pp. 17-18) that, "So influential were al-Nasafi and this one book that, throughout the rest of the century, writers both in and outside the Ismaili fold referred to it as if it represented the intellectual heart of Ismailism."
It is generally agreed upon by the scholars that as-Sijistani was not executed with an-Nasafi in 331/942. The mistake however arose from misreading of al-Baghdadi's statement in "al-Firaq bayn al-Firaq," stating that both an-Nasafi and as-Sijistani were executed. In the introduction of both "Risalat al-Mawazin" and "Risalat al-Mabda wal Ma'ad," he himself mentions the name of Imam al-Hakim, who acceded to the throne in 386/996. Thus, it implies that he was still alive in 386/996. His death, therefore, could be placed between 386/996 and 393/1003. He had managed to escape the widespread massacre, and continued the mission in Bukhara.
Abu Yaqub Ishaq bin Ahmad as-Sijistani, nicknamed "cotton-seed" (Iranian, panba-dana, Arabic khayshafuj) was born in 271/883 and was trained in Yamen. He was a great philosopher and scholar and considered to be one of the major Ismaili thinkers whose share in the development of the Ismaili system of thought is considerable. Paul E. Walker writes, "Yet, from the prominence of his books and the profoundly impressive intellectual contribution they (Ismailis) represent, we discover a truly significant mind and voice - one that deserves recognition as an outstanding figure in the Ismaili past and as a major force in Islamic thought in general" (op. cit., p. 13). He was executed by Khalaf bin Ahmed (363-393/964-1003), the Saffarid ruler of Khorasan. The period of as-Sijistani saw many prominent Ismaili thinkers, such as Abul Haytham Ahmad bin Hasan al-Jurjani, an Ismaili philosopher-poet from Gurgan, who composed many poems on Ismaili doctrines. His Ismaili disciple was Muhammad bin Surkh al-Nishapuri.