Question

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Answer 1

I'm guessing that this has something to do with the Umayyads. Mawali were largely treated like second-class citizens under the Umayyads even when they converted to Islam. As fellow Muslims, they were allowed to pray openly like everyone else and followed most of the same rules as everyone else. They were also allowed to own property. They were just like every other Muslim under the Umayyads - except for the special taxes that were placed on them. Muslims were supposed to be exempt from the taxes that the non-Arab mawali were paying, but even after they became Muslim, they were expected to pay them anyway placing an unfair burden on their shoulders - and eventually leading them to join in the overthrow of the Umayyads.
http://openstudy.com/updates/50548a26e4b02986d3708bb0