This paper sheds light on Ismāʿīl al-Qasṛī, his scholarly and pietist networks, Sufi genealogy, and its later transmission. Other than his debated role in Najm al-Dīn Kubrā's initiation into Sufism, very little is known on this understudied yet significant Sufi from Khuzistan. The paper argues that Ismāʿīl al-Qasṛī and his western Iranian Sufi genealogy was the primary, rather than secondary, initiatory chain claimed by Kubrā, his associates, and the later heritage. Besides, al-Qasṛī's robe continued to be transmitted beyond Kubrā's Sufi chain, and received multiple names in the absence of a prominent, eponymous master to claim it. Also introducing the figures in al-Qasṛī's, and hence Kubrā's, spiritual genealogy, the paper discovers the overlooked yet decisive impact of Iranian masters, most notably the famous pietist of the Fars area, Abū Isḥāq al-Kāzarūnī, on Sufism in the later tradition.