Antiochus IX Eusebes was the son of Antiochus VII Sidetes and Cleopatra Thea. Upon the death of his father in Parthia and his uncle Demetrius II Nicator's return to power (129 BC), his mother sent him to Cyzicus on the Bosporus, thus giving him his nickname. He returned to Syria in 116 BC to claim the Seleucid throne from half-brother/cousin Antiochus VIII Grypus, with whom he eventually divided Syria. He was killed in battle by the son of Grypus, Seleucus VI Epiphanes in 96 BC.