In the late 17th century the diocese severed its ties with Catholicism, along with the rest of the Qudshānis patriarchate, and returned to being traditionalist. The metropolitan bishops of Jīlū were usually nominated from the same clan and all bore the hereditary title Mār Sargīs. An exception to this appears to have been the patriarch Mār Shim'on XV Michael Mukhattas (1740-1780), who is said to have been metropolitan of Jīlū before being elevated to the patriarchate and, indeed, the Cathedral of Sts. Zayʿā and Tāwor is commonly held to have served at certain times as the residence of the patriarchs of that line.