AR23 - Antoninus Pius L Κ

Year 20 of Antoninus Pius's reign, which is what the "L K" regnal date indicates — Egyptian coinage was dated by regnal year rather than the Roman consular system, a bureaucratic holdover from Ptolemaic administrative practice that the Romans never bothered to standardize away. The Alexandria mint produced billon tetradrachms continuously through Pius's remarkably long and stable reign, and the alloy quality by this point had already begun the slow degradation that would accelerate sharply under his successors. Pius never visited Egypt; the province was governed as a personal imperial estate, its mint output tightly controlled from Rome.