Complex sentence: Antiochus V Eupator (c.173 BC-162 BC, reigned 164-162 BC), was only nine when he succeeded as head of the Seleucid dynasty, following the death in Persia of his father Antiochus IV Epiphanes.
Split into simpler sentences: Antiochus V Eupator (c.173 BC-162 BC, ruler of the Greek Seleucid Empire, reigned 164-162 BC). He was only nine when he succeeded to the kingship, following the death in Persia of his father Antiochus IV Epiphanes.