Pompeian era

The calendar counted the years from the region's conquest by the Roman general Pompey in 63 BCE.

Many of these cities had been self-governing poleis before the Jewish Hasmoneans had conquered them in the 2nd century BCE.

The Romans restored their self-governing status, so the conquest amounted to a "new foundation" of the cities, and they made that date the epochal year of their calendars.

However, some cities that ancient writers listed in the Decapolis did not use Pompeian dates.

[3] The region continued to use the Pompeian era during the Byzantine period, long after the term "Decapolis" had fallen out of use.