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I have read that the area roughly corresponding to the satrap of Hyrcania, which included one of the 'Parthian Houses,' the House of Karen, managed to survive the Umayyad conquest of the Sassanid Empire and survived until 760 when it was conquered by the Abbasids.
Would this state have been able to expand its territories or extend its lifetime by taking advantage of the Abbasid overthrow of the Umayyads? Were there any other states that tried to do this?