In 34 BCE, the Roman commander Mark Antony had invaded Armenia and had captured king Artavasdes II. It was Antony's ambition to put a son of the Ptolemaic queen, the famous Cleopatra VII Eupator, and himself, Alexander Helios, on the Armenian throne, but Antony's defeat at Actium prevented this plan. In 31/30, Artavasdes was executed, creating a throne vacancy.
His successor was his son, Artaxias II, who was supported by the Parthians. In 20 BCE, he was killed in a palace coup. His successor was his brother Tigranes III, who was supported by the Roman leader Tiberius, the future emperor.