Nasir Khusraw was a Isma'ili poet, philosopher, traveler, and missionary for the Isma'ili Fatimid Caliphate.
Despite being one of the most prominent Isma'ili philosophers and theologians of the Fatimids and the writer of many philosophical works intended for only the inner circle of the Isma'ili community, Nasir is best known to the general public as a poet and writer who ardently supported his native Persian tongue as an artistic and scientific language. All of Nasir's philosophical Isma'ili works are in Persian, a rarity in the Isma'ili literature of the Fatimids, which primarily used Arabic.
Nasir was a key figure in the spread of Isma'ilism in Central Asia. He is with great reverence called "Pir" or "Shah Sayyid Nasir" by the Isma'ili community of Badakhshan and their branches in northern Pakistan, who all consider him to be their founder.
Wikipedia
translated by Edward. G. Browne, A Literary History of Persia, 1909, p.268
