Year 10 of Marcus Aurelius's reign in Egypt — dated by the regnal calendar rather than the Roman consular system — places this tetradrachm squarely within the Parthian War's aftermath and the catastrophic Antonine Plague, which had arrived in the empire via returning eastern troops around 166 AD and was still killing at scale. Alexandria's mint continued issuing billon tetradrachms with remarkable regularity through these years, though the silver content had been declining steadily for decades before Aurelius ever took the throne.
Year 10 of Marcus Aurelius's reign in Egypt — dated by the regnal calendar rather than the Roman consular system — places this tetradrachm squarely within the Parthian War's aftermath and the catastrophic Antonine Plague, which had arrived in the empire via returning eastern troops around 166 AD and was still killing at scale. Alexandria's mint continued issuing billon tetradrachms with remarkable regularity through these years, though the silver content had been declining steadily for decades before Aurelius ever took the throne.