Phraates (frā–ā´tēz), kings of Parthia of the dynasty of Arsaces. Phraates II, fl. 130 BC, decisively defeated (129 BC) Antiochus VII of Syria, permanently annexing E Mesopotamia to his kingdom. Phraates IV, d. 2 BC, had an early success in driving (36 BC) Antony out of Parthia. After 31 BC, Phraates had to cope with a stubborn rebellion by one of his generals, who briefly usurped the throne. Phraates subsequently acknowledged his dependency to Rome. He died in a palace intrigue.