He was the grandson of the last Umayyad governor of Khurasan, Nasr ibn Sayyar.
[1] His father Layth was likely the "mawla of the amir al-mu'minin" whom Caliph al-Mansur sent as an envoy to the Turkish ruler of Farghana.
Ali's ruthless exploitation of the province and oppressive fiscal measures caused much resentment among the local elites, as well as outbreaks of Kharijite uprisings.
As a result, Harun not only kept him in place, but even accompanied him for part of his return journey, a rare mark of honour.
[3][4] Consequently, when in 806 Rafi launched a revolt in Samarkand,[a] it spread quickly across Khurasan, finding support both among the Arabs and the Iranian natives.