Pre-modern eras •
Anno Mundi [lit. "Year of the World"] (years since the creation of the world) is used in • the
Byzantine calendar (5509 BC). • the
Hebrew calendar (3761 BC). • The
Mesoamerican Long Count Calendar uses the creation of the fourth world in 3114 BC. •
Olympiads, the ancient Greek era of four-year periods between
Olympic Games, beginning in 776 BC. •
Ab urbe condita ("from the foundation of
the city"), used to some extent by
Roman calendars of the Roman imperial period (753 BC). •
Buddhist calendars tend to use the epoch of 544 BC (date of
Buddha's
parinirvana). • The term
Hindu calendar may refer to a number of traditional Indian calendars. A notable example of a Hindu epoch is the
Vikram Samvat (58 BC), also used in modern times as the national calendars of
Nepal and
Bangladesh. • The
Julian and
Gregorian calendars use as epoch the
Incarnation of Jesus as calculated in the 6th century by
Dionysius Exiguus. (Subsequent research has shown that this moment is about four years after the best estimate for the
date of birth of Jesus.) This epoch was applied retrospectively to the Julian calendar, long after its original creation by
Julius Caesar. • The epoch of the
Islamic calendar is the
Hijra (AD 622). The year count in this calendar shifts relative to the solar year count, as the calendar is
purely lunar: its year consists of 12
lunations and is thus ten or eleven days shorter than a solar year. This calendar denotes "lunar years" as
Anno Hegiræ ([since] the year of the
Hijra) or
AH. This calendar is used in
Sunni Islam and related sects. • The epoch of the official
Iranian calendar is also the
Hijra, but it is a
solar calendar; each year begins at the Northern spring equinox. This calendar is used in
Shia Islam and related sects.
Modern eras • The
Bahá'í calendar is dated from the
vernal equinox of the year the
Báb proclaimed his religion (AD 1844). Years are grouped in
Váḥids of 19 years, and
Kull-i-Shay of 361 (19×19) years. • In
Thailand in 1888 King
Chulalongkorn decreed a National Thai Era dating from the founding of
Bangkok on April 6, 1782. In 1912, New Year's Day was shifted to April 1. In 1941,
Prime Minister Phibunsongkhram decided to count the years since 543 BC. This is the
Thai solar calendar using the Thai Buddhist Era. Except for this era, it is the Gregorian calendar. • In the
French Republican Calendar, a calendar used by the French government for about twelve years from late 1793, the epoch was the beginning of the "Republican Era", September 22, 1792 (the day the
French First Republic was proclaimed, one day after the Convention abolished the
Ancien Regime). • The
Indian national calendar, introduced in 1957, follows the
Saka era (AD 78). • The
Minguo calendar used by officials of
Taiwan and
its predecessor dates from January 1, 1912, the first year after the
Xinhai Revolution, which overthrew the
Qing Empire. •
North Korea used a system that starts in 1912 (=
Juche 1), the year of the birth of its founder
Kim Il-Sung until 2024. • The
Fascist Era dates to
Mussolini's
March on Rome in 1922, and was in use only in countries under hegemony of the Fascist regime of Benito Mussolini. It has been defunct since the fall of the
Italian Social Republic in 1945. • In the scientific
Before Present system of numbering years for purposes of
radiocarbon dating, the reference date is January 1, 1950 (though the specific date January 1 is quite unnecessary, as radiocarbon dating has limited precision). • Different branches of
Freemasonry have selected different years to date their documents according to a Masonic era, such as the
Anno Lucis (A.L.). • The
Holocene calendar uses 10,000 BC as the epoch, a rough approximation of the beginning of the
Holocene epoch on the
geological time scale. •
Unix time uses 00:00:00
UTC on 1 January 1970 as the epoch.
Regnal eras The official
Japanese system numbers years from the accession of the current
emperor, regarding the calendar year during which the accession occurred as the first year. A similar
system existed in
China before 1912, being based on the accession year of the emperor (1911 was thus the third year of the
Xuantong period). With the establishment of the
Republic of China in 1912, the republican era was introduced. It is still very common in
Taiwan to date events via the republican era. The People's Republic of China adopted the common era calendar in 1949 (the 38th year of the Chinese Republic). Canada uses regnal eras in the
system it inherited from the United Kingdom for its
Acts of Parliament, where it is currently 4
Charles III; that system was also used in the United Kingdom and Kingdom of England from 1307 until 1963, when
the Gregorian calendar was officially adopted.
Fictional eras • Events in the
Star Wars universe are conventionally dated using an epoch of the
Battle of Yavin. • Events in the
Avatar: The Last Airbender universe are conventionally dated using an epoch of the genocide of the air nomads. == See also ==