Trichalkon - Seleukos II Seleucia ad Tigram

Seleukos II spent much of his reign fighting on two fronts simultaneously — the Third Syrian War against Ptolemy III, who sacked Antioch and briefly seized the Seleucid heartland, and the so-called War of the Brothers against his own sibling Antiochos Hierax, who carved out a semi-independent kingdom in Asia Minor with Galatian mercenary support. Coins struck at Seleucia ad Tigrim during this period were minted at the imperial capital on the Tigris, the administrative and commercial nerve center of the eastern empire.

Seleucia ad Tigrim at this time was among the largest cities in the Hellenistic world, possibly rivaling Alexandria in population.