AR24 - Trajan L ΙΘ

Year 19 of Trajan's reign — the regnal year encoded in that ΙΘ — fell precisely as his Parthian campaign reached its furthest extent. Trajan captured Ctesiphon, declared Mesopotamia a Roman province, and briefly touched the Persian Gulf. Alexandrian tetradrachms of this year were struck in a city that served as the administrative and financial engine of Roman Egypt, its mint operating under tight imperial oversight quite unlike the relatively autonomous mints of the western provinces.

The billon content of Alexandrian tetradrachms had been declining steadily since Nero's currency reforms of 64 AD. By Year 19, these coins were essentially token currency within a closed monetary system — Egyptian residents could not legally exchange them at face value outside the province.