Æ24 - Valerian and Gallienus ΝΙΚΑΙΕΩΝ ΒΥΖΑΝΤΙΩΝ, ΟΜΟΝΟΙΑ

This homonoia issue documents a formal alliance between Nicaea and Byzantium, two cities with a long history of rivalry over regional prestige and commercial dominance in the Propontis. Such concordia coinages were diplomatic instruments — struck to commemorate a specific agreement, treaty, or shared civic honor rather than for routine circulation. The pairing of Valerian and Gallienus as co-emperors dates the issue to their joint reign, though local Bithynian minting was largely winding down by the 260s as the third-century crisis disrupted provincial civic coinage across the empire.