Commagene (kŏməjē´nē), ancient district of N Syria, on the Euphrates River and S of the Taurus range, now in SE Asian Turkey. Its metropolis, Samosata, was founded by Samos, the king of Commagene, c.150 BC The fertile agricultural district was made part of the Assyrian Empire and later of the Persian Empire. In the period after Alexander the Great, it gradually assumed independence under the Seleucid kings of Syria, and its governor, Ptolemy, revolted in 162 BC, declaring absolute independence. The ruling dynasty of independent Commagene was related to the Seleucids. In 64 BC, King Antiochus I, a Roman ally, had his territory enlarged by Pompey, but when he aided the Parthians he was deposed in 38 BC by Antony. The spectacular ruins of Antiochus's tomb and its colossal statues are on Mt. Nemrut. Commagene was annexed by Tiberius (AD 17) but a new king, Antiochus IV, was instated by Caligula (AD 38), was soon deposed, and then reinstated (AD 41) by Claudius. Finally Vespasian permanently annexed Commagene (AD 72) to the Roman province of Syria. The territory was invaded by Khosrow I of Persia in 542, but he withdrew the same year when his campaign was checked by Belisarius.