Other popularly used eras include the Actian (year 1 being 31 B.C., when Marc Antony was defeated by Octavian at the Battle of Actium), the Pompeian (year 1 being 64 B.C.) and the Caesarean (year 1 being 49 B.C., though sometimes it is considered to be 48 or 47 B.C.).

A Nabataean drachm of King Malichus I, dated year 28 (33/2 B.C.).Click image to enlarge.

Foundation dates are also popular, with “year 1” being the year in which a city was founded or regained its freedom.

For the most part, regnal dates were used in Egypt under the Ptolemaic rulers, and with the long series of Roman provincial coins issued at the mint of Alexandria. Though various numbering systems were used to represent the regnal years, the most common was the use of Greek letter(s) with known translations into numbers.

The numbers in such systems are additive, reading from either left to right, or right to left. The table below illustrates the correlations.

1 - A 7 - Z 40 - M 100 - P 2 - B 8 - H 50 - N 200 - Σ or C 3 - Γ 9 - ϴ 60 - Ξ 300 - T 4 - Δ 10 - I 70 - O 400 - Y 5 - E or ε 20 - K 80 - Π 500 - Φ 6 - S or ϛ 30 - Λ 90 - Q 600 - X

Using this system, a coin of year 100 would be dated with just a P, whereas one of year 101 would be dated PA, and one issued in year 152 would be dated PNB.

The city of Tyre began dating their coins fairly early. The earliest of these use a series of Phoenician symbols to represent the dates, whereas the later shekels and half shekels use the Greek letters shown on the table above, with year 1 starting in 126/5 B.C.