AR23 - Marcus Aurelius L Ϛ

Year six of Marcus Aurelius's reign as sole emperor coincided with the catastrophic Antonine Plague, which Roman forces returning from the Parthian War carried back through the eastern provinces beginning around 165 AD. Alexandria, already a densely populated commercial hub on the Nile delta, was among the hardest-hit cities. The plague — likely smallpox — ultimately killed an estimated five million people across the empire over the following decade.

Alexandrian billon tetradrachms of this period show measurable debasement compared to earlier Antonine issues, reflecting pressure on imperial silver reserves from simultaneous military campaigns on the Danube and Parthian fronts.