Also cited as a reason for this campaign was the policy of providing refuge to Sassanids fleeing the Arab advance and to Arab rebels from the Umayyad consolidation of their rule.
The mawali; new non-Arab converts; who were usually allied with Al-Hajjaj's political opponents and thus were frequently forced to participate in battles on the frontier of the Umayyad Caliphate - such as Kabul, Sindh and Transoxania [REF].