Ubaydallah ibn Abdallah ibn Tahir was the last major Tahirid to hold high office in what dynasty?
Ubaydallah ibn Abdallah ibn Tahir Abu Ahmad Ubaydallah ibn Abdallah ibn Tahir (Arabic: أبو أحمد عبيد الله بن عبد الله بن طاهر‎ ‎ , ca. 838 – May 913) was a ninth century Tahirid official and military officer. He was the last major Tahirid to hold high office, having served as the governor of Baghdad at various points between 867 and 891.
Muhammad at-Taqi (Ahmed ibn Abadullah) Muhammad at-Taqi (True name: Aḥmad ibn ʿAbd Allāh ibn Muḥammad ibn Ismāʿīl (أحمد بن عبد اللّه بن محمد بن إسماعيل) or Aḥmad ibn ʿAbd Allāh ibn Muḥammad at-Taqi) (born AH 198 (1+((198-1)*354.367+227015)/365.25-0.505 round0/2+((198-1)*354.367+227015)/365.25-0.5 round0) , died AH 225 (1+((225-1)*354.367+227015)/365.25-0.505 round0/2+((225-1)*354.367+227015)/365.25-0.5 round0) , Salamia, Syria, Imam: AH 212 (1+((212-1)*354.367+227015)/365.25-0.505 round0/2+((212-1)*354.367+227015)/365.25-0.5 round0) -AH 225 (1+((225-1)*354.367+227015)/365.25-0.505 round0/2+((225-1)*354.367+227015)/365.25-0.5 round0) ) is the ninth Ismāʿīlī Imam . As the Imam, he was the supreme spiritual leader of the Ismāʿīlī community from his appointment until his death. The Nizari and Mustaali trace their Imamate lines from him and his descendants who founded the Fatimid Empire. He was succeeded by his son, Ḥusayn ibn Aḥmad /Raḍī ʿAbd Allāh.