In the year A. H. 240 (A. D. 854—5) the Caliph al-Mu'­taṣim sent one of his nobles to the Ispahbad Qárin the son of Shahriyár, king of the mountains, to bid him break his Magian girdle and embrace Islám, which he did, and there­upon received a robe of honour from the Caliph. At this time Muḥammad b. 'Isa was governing Ṭabaristán, as deputy for the Ṭáhirids, and his government was just and mild. Then Sulaymán b. 'Abdu`lláh was sent to replace him, and he nominated first Quraysh and then Asad b. Jandán as his deputies, and later Muḥammad b. Aws, who united Rúyán and Jálús, placing his son Aḥmad in the latter place, as governor over it and Kalár; but his tyranny and harshness were such that all who were able sold or abandoned their houses and migrated elsewhere. And every year the taxes were levied three times; once for Muḥammad b. Aws, once for his son, and once for a Magian who acted as their agent.