Æ20 - Valerian and Gallienus C G IVL H PAR

Parium, a Roman colony on the southern Marmara coast, retained the right to strike local bronze under the joint reign of Valerian I and his son Gallienus — a pairing formalized when Valerian elevated Gallienus to co-emperor in 253 AD to manage the western provinces while he faced mounting pressure on the eastern frontier. That arrangement ended abruptly in 260 when Valerian was captured by Shapur I at the Battle of Edessa, the first Roman emperor ever taken prisoner by a foreign enemy. Coins naming both rulers therefore compress into a tight seven-year window.