Ubaydallah ibn Abdallah ibn Tahir was the last major Tahirid to hold high office in what dynasty?
Tahirid dynasty The Tahirid dynasty (Persian: طاهریان‎ ‎ , "Tâhereyân") was a dynasty, of Persian dihqan origin, that governed the Abbasid province of Khorasan from 821 to 873 and the city of Baghdad from 820 until 891. The dynasty was founded by Tahir ibn Husayn, a leading general in the service of the Abbasid caliph al-Ma'mun. Their capital in Khorasan was initially located at Merv but was later moved to Nishapur. The Tahirids enjoyed a high degree of autonomy in their governance of Khorasan, but they remained subject to the Abbasid caliphate and were not independent rulers.
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.