The Seleucids amassed a large force of Greek mercenaries and led the army, totaling 80,000 soldiers, to confront the Parthians, initiating a campaign in 130 BC to retake Mesopotamia.

Antiochus refused to accept unless the Arsacids relinquished all lands to him except Parthia proper, paid heavy tribute, and released his brother Demetrius II from captivity.

By spring 129 BC, the Medes were in open revolt against Antiochus, whose army under Athenaeus of Macedonia had exhausted the resources of the countryside during winter.

[6][7] His body was sent back to Syria in a silver coffin; his son Seleucus was made a Parthian hostage[8] and a daughter joined Phraates' harem.

[9] After the Battle of Ecbatana, the rest of the Seleucid army which was based in Media was largely destroyed, and the remainder was captured and folded into Parthian ranks.