AR24 - Antoninus Pius L ΚΒ

Year 22 of Antoninus Pius's reign — 158–159 AD — falls deep into one of the most administratively stable periods of Roman rule in Egypt, which is precisely why Alexandrian billon tetradrachms from this regnal year survive in relatively consistent numbers. The mint at Alexandria operated under strict prefectural oversight, producing a closed currency system that prevented Roman silver from circulating locally and kept provincials dependent on this debased local coinage.

The billon content by this point in the reign had declined noticeably from earlier issues, a gradual debasement that accelerated further under Marcus Aurelius.