Jewish Chronology

Major methods of counting years according to the Jewish sources (Avodah Zara 9)

1. For private records and Temple histories, an initial era was established, one that measured from the Exodus from Egypt. An example of this can be seen in I Kings 6:1, where the date for the construction of the First Temple is given as 480 of the Exodus era.
2. During the fourth century B.C.E., a dating system was sought out for secular use on business and legal documents. At this time, the Jews borrowed the practice of the Greeks, who had introduced the practice of numbering time in “eras”–periods of time relative to a historical event, rather than the lifetime or rule of any one person. This new system is called the “Seleucid Era” by secular scholars and, in Jewish circles, it is known as “Minyan Shtaros” – “accounting of contracts.” It counts time from the year 312-311 B.C.E., six years following the arrival of Alexander in the region with his firm establishment of control. Others state this dating system began after the encounter between Alexander and Shimon haTzadik (Yuma 69a). Since Alexander agreed to not destroy the Bais haMikdash, the Jews began for the next year naming all Jewish boys with being named Alexander and a new reckoning of the years beginning the next attributed to him. This era began exactly 1000 years after the Exodus from Egypt and the Giving of the Torah at Har Sinai. This new method of counting marked the end of the era of prophecy and the beginning of the era where the Sages were the spiritual leaders.
3. Counting from the Churban of the Second Bais haMikdash was used mostly in Eretz Yisrael.
4. The counting of Jewish years, as we know it today, dates from the middle Ages. In secular texts, Jewish time is often noted as “A.M.” — anno mundo — literally, “years of the world.” (Occasionally, “A.M.” is explained as standing for aera mundi, “era of the world.”) This system of Jewish time is called the “Mundane Era” (English for aera mundi) because those who invented it believed they were calculating dates from the birth of the world. Torah does not list historical years but does provide the lifetimes of people and the Kings
5. Finally, the system of counting that counts the present year as 2018 was invented by a Christian monk named Dionysius Exodus (the latter word means “the humble”) in the early sixth century C.E.(Common Era) He did not like the system in use in his time, which was pegged to Roman emperors who were notorious for persecuting Christians. Accordingly, he invented a system where year 1 was the year that Jesus was born. (But he was wrong in his assumed year of Jesus’ birth; Jesus was born a few years earlier.) It took about 200 years for the counting system of Dionysius to become the standard one for the general world and even later for the Jewish communities in the Diaspora.

Please note two discussions points:

1. Reckoning of year one of the A.M. (after Creation) system. In the East (including the Gemara Bavli and the Rishonim that explain the Gemara) the custom was to count year one from the creation of the first man on the 1st of Tishrei. However, in Eretz Yisrael people counted from the Creation of the World and the first year lasted for 5 days, and the second year began with the birth of the first man. The system used by Gemara and the Rishonim fell into misuse and the second system was used by most. Thus, the two systems always differ by one year (in order to fully understand the Rishonim).
2. Thus, according to the Gemara system of counting, the first year of the Minyan Shtaros was 3450 A.M. and the year of the Churban Bayis Sheni was 3830 A.M.; whereas the prevailing system the first year of Minyan Shtaros was 3449 A.M. and the Churban occurred in 3829 A.M.

Examples:

Years of the World A.M.Era of ContractsSince the ExodusPost-ChurbanCommon Era C.E.2449-1-1312-1311 B.C.E.344911001-312-311 B.C.E.38293811381169-70 C.E.40005521552172240-241 C.E.5778-333019502017-2018 C.E.