Antiochus' year of birth is not specified by ancient historians, but his portrait known from his coins indicate that he was approximately five years old when he assumed the throne in 175 BC. He was the younger son of King Seleucus IV and his wife Laodice IV.[1] The Empire was obligated by the 188 BC Treaty of Apamea, signed after King Antiochus III lost a war against the Romans, to send a hostage to Rome; at first, Antiochus' uncle Antiochus IV was sent as a hostage. After Antiochus III's death in 187 BC, Seleucus IV replaced his brother Antiochus IV with his own eldest son and heir Demetrius I, since Rome considered it important that a son of the reigning king be a hostage.