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.