Justan III

[1] In 869, the Abbasid military officer Muflih al-Turki invaded Tabaristan, and defeated Justan at the nearby city of Qazvin.

Some time later, Justan welcomed another Alid named Hasan al-Utrush, who had taken refugee at Ray after the Samanid conquest of Tabaristan.

He therefore went on a mission to the as-yet unconverted Gilites and Dailamites to the north of the Alborz mountains, where he preached in person and founded mosques.

His efforts were swiftly crowned by success: the mountain Daylamites and the Gilites east of the Safid Rud river recognized him as their imam with the name of al-Nāṣir li'l-Ḥaqq ("Defender of the True Faith") and were converted to his own branch of Zaydi Islam, which was named after him as the Nasiriyya and differed in some practices from the "mainstream" Qasimiyya branch adopted in Tabaristan following the teachings of Qasim ibn Ibrahim.

[8] However, Justan's murder was shortly avenged by his son-in-law Muhammad ibn Musafir[8] who had married his daughter Kharasuya[9] and was from another Dailamite dynasty known as the Sallarids, which ruled over Tarum.