father to Al-Ma'mun’s Iranian mother, Marajil, which would make him Ma'mūn's maternal grandfather.
Based in the eastern fringe of Khorasan, in the mid-8th-century he claimed he was a prophet of God and managed to gain followers among the villagers in that area.
Many were previously followers of Bihafarid, whom the Abbasid commander, Abu Muslim, had crushed militarily.
[1] His initial base was the mountainous region of Badghis, and he soon occupied Herat and Sistan before marching towards Merv.
[1] Ustadh Sis managed to flee to the mountains, but Abbasid general Khazim ibn Khuzayma al-Tamimi followed him and was able to capture him.