At-Tayyib Abi L-Qasim
aṭ-Ṭayyib Abī l-Qāṣim (Arabic: الطيب أبي القاسم) was, according to Ṭayyibī Musta‘lid Isma‘ili Muslims, the 21st and (as some} believe) the last Fatimid Imām (the hereditary leader of the Muslim community in the direct line of ‘Ali). Abī l-Qāṣim was the son of the 20th Fatimid Imām, Mansur al-Amir Bi-Ahkamillah who ruled Egypt from 1101-1130. He was born in Al-Moizziyyatul Qaherah on Sunday the 4th of Rabiul Aakher, 524H.
According to Ṭayyibī Musta‘lid tradition, before Ṭayyib went into seclusion his father al-Amir instructed Queen al-Hurrah Arwa al-Sulayhi in Yemen to anoint a vicegerent after the seclusion. The vicegerent, or Da'i al-Mutlaq, would have full authority to govern the community in all matters both spiritual and temporal. She appointed Dai Zoeb bin musa as First Dai.
Dai Zoeb lived and died in Haus, Yemen. His Mazoon was Syedna Khattab bin Hasan. After the death of Maoulai Abadullah, Dai Zoeb appointed Moulai Yaqoob to be Wali ("representative" or "caretaker") of the Fatimid Dawat in India.
Moulai Yaqoob was the first person of Indian origin to receive this honour. He was son of Moulai Bharmal, minister of Rajput King Siddhraja Jaya Singha. They all, along with minister Moulai Tarmal, had honoured Fatimid Dawat along with their fellow citizens on the call of Moulai Abdullah. Moulai Fakhruddin, son of Moulai Tarmal, was then sent to western Rajasthan, India.
The line of the Dais continued until the 24th Dai Yusuf bin Sulayman in Yemen. Due to prosecution by the local ruler, the Dawat then shifted to India under the 25th Dai Jalal bin Hasan.
As of 2011 Fatimid/Taiyabi/Dawoodi Bohra Dawa is headed by the 52nd dai Mohammad Burhanuddin.
Hafizi Musta‘li Isma‘ilis were those who continued to accept the legitimacy of the Fatimid rulers of Egypt between 1130-1169 instead of aṭ-Ṭayyib Abī l-Qāṣim. After the end of their rule by Saladin they are apparently extinct.