The Seleucid era ("SE") or Anno Graecorum (literally "year of the Greeks" or "Greek year"), sometimes denoted "AG," was a system of numbering years in use by the Seleucid Empire and other countries among the ancient Hellenistic civilizations. It is sometimes referred to as "the dominion of the Seleucidæ," or the Year of Alexander. The era dates from Seleucus I Nicator's re-conquest of Babylon in 312/11 BC after his exile in Ptolemaic Egypt, considered by Seleucus and his court to mark the founding of the Seleucid Empire. According to Jewish tradition, it was during the sixth year of Alexander the Great's reign (lege: possibly Alexander the Great's infant son, Alexander IV of Macedon) that they began to make use of this counting. The introduction of the new era is mentioned in one of the Babylonian Chronicles, the Chronicle of the Diadochi.
Two different variations of the Seleucid years existed, one where the year started in spring and another where it starts in autumn:
These differences in the beginning of the year means that dates differ by one if they fall between spring and autumn. Notably, the Jewish historical book 1 Maccabees generally uses the Babylonian and Judean year count (1 Maccabees 6:20, 1 Maccabees 7:1, 9:3, 10:1, etc.). However, the book 2 Maccabees exclusively uses the Macedonian version of the calendar, likely because it was written in either Cyprus or Egypt. (Both books are regarded as either canonical or deuterocanonical by certain Christian denominations.) Elias Bickerman gives this example:
The Seleucid era was used as late as the 6th century AD, for instance in the Zabad trilingual inscriptionin Syria, dated the 24th of Gorpiaios, 823 (24 September, 512 AD), and in the writings of John of Ephesus. Syriac chroniclers continued to use it up to Michael the Syrian in the 12th century AD / 15th century AG. It has been found on Central Asian tombstones of Christians belonging to the Church of the East well into the 14th century AD.
The Seleucid era counting, or "era of contracts" (minyan sheṭarot), was used by Yemenite Jews in their legal deeds and contracts until modern times, a practice derived from an ancient Jewish teaching in the Talmud, requiring all Diaspora Jews to uphold its practice. For this reason, the Seleucid era counting is mentioned in the Book of Maccabees (I Macc. i. 11) and in the writings of the historian, Josephus. The Seleucid era counting fell into disuse among most Jewish communities, following Rabbi David ben Zimra's cancellation of the practice when he served as Chief Rabbi of Egypt.
In the year of the Greeks one thousand and ninety-two, the Lord Jazedbuzid, Priest and Vicar-episcopal of Cumdan the royal city, son of the enlightened Mailas, Priest of Balach a city of Turkestan, set up this tablet, whereon is inscribed the Dispensation of our Redeemer, and the preaching of the apostolic missionaries to the King of China. ["The Priest Lingpau", in Chinese] "Adam the Deacon, son of Jazedbuzid, Vicar-episcopal. The Lord Sergius, Priest and Vicar-episcopal. Sabar Jesus, Priest. Gabriel, Priest, Archdeacon, and Ecclesiarch of Cumdan and Sarag.
Once local and irregular, time-keeping became universal and linear in 311 BCE. History would never be the same again.