Ancient and earlier medieval coins are often dated by regnal year, not by year-dates of the Julian/Gregorian calendar. The practice of applying Common Era dates to coinage began in the thirteenth century, with the first Common Era date borne by a coin being 1234, applied to a bronze coin struck in Denmark under the reign of Valdemar II. This bronze coin has the date in Roman numerals on the reverse. Seven examples are known, one of which resides in private hands. That the first Common Era date featured on a coin is composed of ascending digits is certainly interesting.
Another coin struck in the early thirteenth century which could plausibly claim the moniker of “first Common Era-dated coin,” a silver obol struck in Toledo in 1166. It bears the date 1204 of the “Hispanic Era,” a dating system in use on the Iberian Peninsula in the Middle Ages.
Blog readers are encouraged to check out Robert A. Levinson’s The Early Dated Coins of Europe, 1234-1500.
A useful CoinsWeekly piece on the issue: https://coinsweekly.com/two-contenders-for-the-first-christian-era-dated-coin/
