AR18 - Diocletian L ΕΝΑΤΟΥ, Β

Year nine of Diocletian's reign coincided almost exactly with his proclamation of the Tetrarchy — the administrative division of the empire into four co-rulers formalized in 293 AD. Alexandria's mint had been producing these billon tetradrachms continuously since the Ptolemaic monetary system was absorbed into Rome, and by Diocletian's time the silver content had fallen so low that "billon" is a generous description. The L ΕΝΑΤΟΥ regnal date formula is the last year before the Diocletianic coinage reform of 294 effectively terminated the Alexandrian tetradrachm series after roughly five centuries of unbroken production.