Tetradrachm - Antiochos I Soter Seleukeia on the Tigris

Antiochos I inherited an empire in crisis. His father Seleukos I was assassinated in 281 BC just months after finally consolidating control over Macedonia, leaving Antiochos to manage simultaneous pressure from Ptolemaic Egypt in the south and the catastrophic Galatian invasions of Asia Minor — migrations of Celtic tribes whose raiding had destabilized the entire Anatolian interior through the 270s BC. His decisive defeat of the Galatians, probably around 275 BC, earned him the epithet Soter, "Savior."

Seleukeia on the Tigris was the administrative and commercial heart of the eastern empire, founded by Seleukos I on the west bank of the Tigris near Babylon. Output from this mint under Antiochos I was substantial.