|Ab urbe condita||2773|
|Balinese saka calendar||1941–1942|
|British Regnal year||68 Eliz. 2 – 69 Eliz. 2|
|Chinese calendar|| 己亥年 (Earth Pig)|
4716 or 4656
— to —
庚子年 (Metal Rat)
4717 or 4657
|- Vikram Samvat||2076–2077|
|- Shaka Samvat||1941–1942|
|- Kali Yuga||5120–5121|
|Japanese calendar|| Reiwa 2|
|Julian calendar||Gregorian minus 13 days|
|Minguo calendar|| ROC 109|
|Thai solar calendar||2563|
2146 or 1765 or 993
— to —
2147 or 1766 or 994
|Unix time||1577836800 – 1609459199|
A calendar era is the period of time elapsed since one epoch of a calendar and, if it exists, before the next one.For example, the Gregorian calendar numbers its years in the Western Christian era (the Coptic Orthodox and Ethiopian Orthodox churches have their own Christian eras).
In antiquity, regnal years were counted from the accession of a monarch. This makes the Chronology of the ancient Near East very difficult to reconstruct, based on disparate and scattered king lists, such as the Sumerian King List and the Babylonian Canon of Kings. In East Asia, reckoning by era names chosen by ruling monarchs ceased in the 20th century except for Japan, where they are still used.
For over a thousand years, ancient Assyria used a system of eponyms to identify each year. Each year at the Akitu festival (celebrating the Mesopotamian new year), one of a small group of high officials (including the king in later periods) would be chosen by lot to serve as the limmu for the year, which meant that he would preside over the Akitu festival and the year would bear his name. The earliest attested limmu eponyms are from the Assyrian trading colony at Karum Kanesh in Anatolia, dating to the very beginning of the 2nd millennium BC,and they continued in use until the end of the Neo-Assyrian Period, ca. 612 BC.
Assyrian scribes compiled limmu lists, including an unbroken sequence of almost 250 eponyms from the early 1st millennium BC. This is an invaluable chronological aid, because a solar eclipse was recorded as having taken place in the limmu of Bur-Sagale, governor of Guzana. Astronomers have identified this eclipse as one that took place on 15 June 763 BC, which has allowed absolute dates of 892 to 648 BC to be assigned to that sequence of eponyms.This list of absolute dates has allowed many of the events of the Neo-Assyrian Period to be dated to a specific year, avoiding the chronological debates that characterize earlier periods of Mesopotamian history.
Among the ancient Greek historians and scholars, a common method of indicating the passage of years was based on the Olympic Games, first held in 776 BC. The Olympic Games provided the various independent city-states with a mutually recognizable system of dates. Olympiad dating was not used in everyday life. This system was in use from the 3rd century BC. The modern Olympic Games (or Summer Olympic Games beginning 1896) do not continue the four year periods from ancient Greece: the 669th Olympiad would have begun in the summer of 1897, but the modern Olympics were first held in 1896. 769:
Another common system was the indiction cycle (15 indictions made up an agricultural tax cycle in Roman Egypt, an indiction being a year in duration). Documents and events began to be dated by the year of the cycle (e.g., "fifth indiction", "tenth indiction") in the 4th century, and this system was used long after the tax ceased to be collected. It was used in Gaul, in Egypt until the Islamic conquest, and in the Eastern Roman Empire until its conquest in 1453.
The rule for computing the indiction from the AD year number, which he had just invented, was stated by Dionysius Exiguus: add 3 and divide by 15; the remainder is the indiction, with 0 understood to be the fifteenth indiction. 770 Thus 2001 was the ninth indiction. The beginning of the year for the indiction varied. :769–71:
The Seleucid era was used in much of the Middle East from the 4th century BC to the 6th century AD, and continued until the 10th century AD among Oriental Christians. The era is computed from the epoch 312 BC: in August of that year Seleucus I Nicator captured Babylon and began his reign over the Asian portions of Alexander the Great's empire. Thus depending on whether the calendar year is taken as starting on 1 Tishri or on 1 Nisan (respectively the start of the Jewish civil and ecclesiastical years) the Seleucid era begins either in 311 BC (the Jewish reckoning) or in 312 BC (the Greek reckoning: October–September).
An early and common practice was Roman 'consular' dating. This involved naming both consules ordinarii who had taken up this office on 1 January (since 153 BC) of the relevant civil year. 6 Sometimes one or both consuls might not be appointed until November or December of the previous year, and news of the appointment may not have reached parts of the Roman empire for several months into the current year; thus we find the occasional inscription where the year is defined as "after the consulate" of a pair of consuls.:
The use of consular dating ended in AD 541 when the emperor Justinian I discontinued appointing consuls. The last consul nominated was Anicius Faustus Albinus Basilius. Soon afterwards, imperial regnal dating was adopted in its place.
Another method of dating, rarely used, was anno urbis conditae (Latin: "in the year of the founded city" (abbreviated AUC), where "city" meant Rome). (It is often incorrectly given that AUC stands for ab urbe condita , which is the title of Titus Livius's history of Rome.)
Several epochs were in use by Roman historians. Modern historians usually adopt the epoch of Varro, which we place in 753 BC.
The system was introduced by Marcus Terentius Varro in the 1st century BC. The first day of its year was Founder's Day (21 April), although most modern historians assume that it coincides with the modern historical year (1 January to 31 December). It was rarely used in the Roman calendar and in the early Julian calendar – naming the two consuls that held office in a particular year was dominant. AD 2020 is thus approximately the same as AUC 2773 (2020 + 753).
About AD 400, the Iberian historian Orosius used the AUC era. Pope Boniface IV (about AD 600) may have been the first to use both the AUC era and the Anno Domini era (he put AD 607 = AUC 1360).[ citation needed ]
Another system that is less commonly found than might be thought was the use of the regnal year of the Roman emperor. At first, Augustus indicated the year of his reign by counting how many times he had held the office of consul, and how many times the Roman Senate had granted him Tribunican powers, carefully observing the fiction that his powers came from these offices granted to him, rather than from his own person or the many legions under his control. His successors followed his practice until the memory of the Roman Republic faded (about AD 200), when they began to use their regnal year openly.
Some regions of the Roman Empire dated their calendars from the date of Roman conquest, or the establishment of Roman rule.
The Spanish era counted the years from 38 BC, probably the date of a new tax imposed by the Roman Republic on the subdued population of Iberia. The date marked the establishment of Roman rule in Spain and was used in official documents in Portugal, Aragon, Valencia, and in Castile, into the 14th century. This system of calibrating years fell to disuse in 1381 and was replaced by today's Anno Domini.
Throughout the Roman and Byzantine periods, the Decapolis and other Hellenized cities of Syria and Palestine used the Pompeian era, counting dates from the Roman general Pompey's conquest of the region in 63 BC.
A different form of calendar was used to track longer periods of time, and for the inscription of calendar dates (i.e., identifying when one event occurred in relation to others). This form, known as the Long Count, is based upon the number of elapsed days since a mythological starting-point. According to the calibration between the Long Count and Western calendars accepted by the great majority of Maya researchers (known as the GMT correlation), this starting-point is equivalent to 11 August, 3114 BC in the proleptic Gregorian calendar or 6 September in the Julian calendar (−3113 astronomical).
A great many local systems or eras were also important, for example the year from the foundation of one particular city, the regnal year of the neighboring Persian emperor, and eventually even the year of the reigning Caliph.
Most of the traditional calendar eras in use today were introduced at the time of transition from Late Antiquity to the Early Middle Ages, roughly between the 6th and 10th centuries.
The era based on the Incarnation of Christ was introduced by Dionysius Exiguus in 525 and is in continued use with various reforms and derivations. The distinction between the Incarnation being the conception or the Nativity of Jesus was not drawn until the late ninth century. 881 The beginning of the numbered year varied from place to place: when, in 1600, Scotland adopted 1 January as the date the year number changes, this was already the case in much of continental Europe. England adopted this practice in 1752. :7:
The Hindu Saka Era influences the calendars of southeast Asian indianized kingdoms.
The terms anno Domini (AD) and before Christ (BC) are used to label or number years in the Julian and Gregorian calendars. The term anno Domini is Medieval Latin and means "in the year of the Lord", but is often presented using "our Lord" instead of "the Lord", taken from the full original phrase "anno Domini nostri Jesu Christi", which translates to "in the year of our Lord Jesus Christ".
Ab urbe condita, or Anno urbis conditae, often abbreviated as AUC in either case, is a convention that was used in antiquity and by classical historians to refer to a given year in Ancient Rome. Ab urbe condita is rendered into idiomatic English as "from the founding of the City", while anno urbis conditae likewise translates to "in the year since the City's founding". Therefore, the traditional year of the foundation of Rome, 753 BC, would be written AUC 1, while AD 1 would be AUC 754. The foundation of the Empire in 27 BC would be AUC 727.
A calendar is a system of organizing days for social, religious, commercial or administrative purposes. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single, specific day within such a system. A calendar is also a physical record of such a system. A calendar can also mean a list of planned events, such as a court calendar or a partly or fully chronological list of documents, such as a calendar of wills.
Common Era (CE) is one of the notation systems for the world's most widely used calendar era. BCE is the era before CE. BCE and CE are alternatives to the Dionysian BC and AD system respectively. The Dionysian era distinguishes eras using AD and BC. Since the two notation systems are numerically equivalent, "2020 CE" corresponds to "AD 2020" and "400 BCE" corresponds to "400 BC". Both notations refer to the Gregorian calendar. The year-numbering system used by the Gregorian calendar is used throughout the world today, and is an international standard for civil calendars.
An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth.
The Julian calendar, proposed by Julius Caesar in 708 AUC (46 BC), was a reform of the Roman calendar. It took effect on 1 January 709 AUC (45 BC), by edict. It was designed with the aid of Greek mathematicians and Greek astronomers such as Sosigenes of Alexandria.
AD 1 (I), 1 AD or 1 CE is the epoch year for the Anno Domini calendar era. It was the first year of the Common Era (CE), of the 1st millennium and of the 1st century. It was a common year starting on Saturday or Sunday, a common year starting on Saturday by the proleptic Julian calendar, and a common year starting on Monday by the proleptic Gregorian calendar. In its time, year 1 was known as the Year of the Consulship of Caesar and Paullus, named after Roman consuls Gaius Caesar and Lucius Aemilius Paullus, and less frequently, as year 754 AUC within the Roman Empire. The denomination "AD 1" for this year has been in consistent use since the mid-medieval period when the anno Domini (AD) calendar era became the prevalent method in Europe for naming years. It was the beginning of the Christian/Common era. The preceding year is 1 BC; there is no year 0 in this numbering scheme. The Anno Domini dating system was devised in AD 525 by Dionysius Exiguus.
The proleptic Julian calendar is produced by extending the Julian calendar backwards to dates preceding AD 8 when the quadrennial leap year stabilized. The leap years that were actually observed between the implementation of the Julian calendar in 45 BC and AD 8 were erratic: see the Julian calendar article for details.
Julian day is the continuous count of days since the beginning of the Julian Period and is used primarily by astronomers, and in software for easily calculating elapsed days between two events.
An epoch, for the purposes of chronology and periodization, is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured.
Chronology is the science of arranging events in their order of occurrence in time. Consider, for example, the use of a timeline or sequence of events. It is also "the determination of the actual temporal sequence of past events".
The Coptic calendar, also called the Alexandrian calendar, is a liturgical calendar used by the Coptic Orthodox Church and also used by the farming populace in Egypt. This calendar is based on the ancient Egyptian calendar. To avoid the calendar creep of the latter, a reform of the ancient Egyptian calendar was introduced at the time of Ptolemy III which consisted of the intercalation of a sixth epagomenal day every fourth year. However, this reform was opposed by the Egyptian priests, and the reform was not adopted until 25 BC, when the Roman Emperor Augustus imposed the Decree upon Egypt as its official calendar. To distinguish it from the Ancient Egyptian calendar, which remained in use by some astronomers until medieval times, this reformed calendar is known as the Coptic calendar. Its years and months coincide with those of the Ethiopian calendar but have different numbers and names.
The history of calendars, that is, of people creating and using methods for keeping track of days and larger divisions of time, covers a practice with ancient roots.
The Ethiopian calendar or Eritrean calendar is the principal calendar used in Ethiopia and also serves as the liturgical year for Christians in Eritrea and Ethiopia belonging to the Eritrean Orthodox Tewahedo Church, Ethiopian Orthodox Tewahedo Church, Eastern Catholic Churches, the Coptic Orthodox Church of Alexandria, and P'ent'ay Churches. The Ethiopian calendar is a solar calendar which in turn derives from the Egyptian calendar, but like the Julian calendar, it adds a leap day every four years without exception, and begins the year on August 29 or August 30 in the Julian calendar. A gap of seven to eight years between the Ethiopian and Gregorian calendars results from an alternative calculation in determining the date of the Annunciation.
The Era of the Martyrs, also known as the Diocletian era, is a method of numbering years used by the Church of Alexandria beginning in the 4th century AD and by the Coptic Orthodox Church of Alexandria from the 5th century to the present. Western Christians were aware of it but did not use it. It was named for the Roman Emperor Diocletian who instigated the last major persecution against Christians in the Empire. Diocletian began his reign 20 November 284 during the Alexandrian year that began on 1 Thoth, the Egyptian New Year, or 29 August 284, so that date was used as the epoch: year one of the Diocletian era began on that date. This era was used to number the year in Easter tables produced by the Church of Alexandria.
Anno Mundi, abbreviated as AM, or Year After Creation, is a calendar era based on the biblical accounts of the creation of the world and subsequent history. Two such calendar eras have seen notable use historically:
A regnal year is a year of the reign of a sovereign, from the Latin regnum meaning kingdom, rule. Regnal years considered the date as an ordinal, not a cardinal number. For example, a monarch could have a first year of rule, a second year of rule, a third year of rule, and so on, but not a zeroth year of rule.
The Holocene calendar, also known as the Holocene Era or Human Era (HE), is a year numbering system that adds exactly 10,000 years to the currently dominant numbering scheme, placing its first year near the beginning of the Holocene geological epoch and the Neolithic Revolution, when humans transitioned from a hunter-gatherer lifestyle to agriculture and fixed settlements. The current year by the Gregorian calendar, AD 2020, is 12020 HE in the Holocene calendar. The HE scheme was first proposed by Cesare Emiliani in 1993.
The year zero does not exist in the Anno Domini (AD) system commonly used to number years in the Gregorian calendar and in its predecessor, the Julian calendar. In this system, the year 1 BC is followed by AD 1. However, there is a year zero in astronomical year numbering and in ISO 8601:2004, as well as in all Buddhist and Hindu calendars.
The Spanish era, sometimes called the era of Caesar, was a calendar era commonly used in the states of the Iberian Peninsula from the 5th century until the 15th, when it was phased out in favour of the Anno Domini (AD) system. The epoch of the Spanish era was 1 January 38 BC. To convert an Anno Domini date to the corresponding year in the Spanish era, add 38 to the Anno Domini year, such that Era 941 would be equivalent to AD 903. A date given in the Spanish era always uses the word era followed by a feminine ordinal number. This contrasts with the AD system that uses the masculine anno (year): i.e., era millesima octava versus anno millesimo octavo.