History Main / HitSoHardTheCalendarFeltIt

** Regnal dating, combined with the loss of historical records for ''entire periods of reign'' makes the [[UsefulNotes/AncientEgyptianHistory Egyptian dynastic timeline]] a matter of ''extremely'' hot debate in Egyptology circles. While some gaps are simply due to the loss of records over time, others are due to various pharaohs [[UnPerson purging the official records of any mention of their rivals or predecessors, and deliberately destroying or defacing monuments]]. It also doesn't help that the Egyptians had a strong aversion--bordering on a taboo--towards stating the date or circumstances of royal deaths in the annals and the royal funerary texts and inscriptions. Thus what would be a pretty normal, even standard, entry in the annals of most other historical monarchies--"His Majesty died in the twenty-fifth year of his reign of [[Literature/TenSixtySixAndAllThat a surfeit of palfreys]]"--would be a marvelous find (suspiciously marvelous, in fact) for an Egyptologist.

** Regnal dating, combined with the loss of historical records for ''entire periods of reign'' makes the [[UsefulNotes/AncientEgyptianHistory Egyptian dynastic timeline]] a matter of ''extremely'' hot debate in Egyptology circles. While some gaps are simply due to the loss of records over time, others are due to various pharaohs [[UnPerson purging the official records of any mention of their rivals or predecessors, and deliberately destroying or defacing monuments]]. It also doesn't help that the Egyptians had a strong aversion--bordering on a taboo--towards stating the date or circumstances of royal deaths in the annals and the royal funerary texts and inscriptions. Thus what would be a pretty normal, even standandard, entry in the annals of most other historical monarchies--"His Majesty died in the twenty-fifth year of his reign of [[Literature/TenSixtySixAndAllThat a surfeit of palfreys]]"--would be a marvelous find (suspiciously marvelous, in fact) for an Egyptologist.

** Regnal dating, combined with the loss of historical records for ''entire periods of reign'' makes the [[UsefulNotes/AncientEgyptianHistory Egyptian dynastic timeline]] a matter of ''extremely'' hot debate in Egyptology circles. While some gaps are simply due to the loss of records over time, others are due to various pharaohs [[UnPerson purging the official records of any mention of their rivals or predecessors, and deliberately destroying or defacing monuments]]. It also doesn't help that the Egyptians had a strong aversion--bordering on a taboo--towards stating the date or circumstances of royal deaths in the annals and the royal funerary texts and inscriptions. Thus what would be a pretty normal, even standandard, entry in the annals of most other historical monarchies--"His Majesty died in the twenty-fifth year of his reign of [[Literature/1066AndAllThat a surfeit of palfreys]]"--would be a marvelous find (suspiciously marvelous, in fact) for an Egyptologist.

** Regnal dating, combined with the loss of historical records for ''entire periods of reign'' makes the [[UsefulNotes/AncientEgyptianHistory Egyptian dynastic timeline]] a matter of ''extremely'' hot debate in Egyptology circles. While some gaps are simply due to the loss of records over time, others are due to various pharaohs [[UnPerson purging the official records of any mention of their rivals or predecessors, and deliberately destroying or defacing monuments]].

** The Romans did not usually use a continuous numbering system for their years, the way we do. Unique years were identified with reference to the political leadership of the state. Under the monarchy, this meant regnal years (the Xth year of King Y's reign). Under the Republic, they referred to the years as "[the year] ''X'' and ''Y'' being consul," which, naturally, [[ExactlyWhatItSaysOnTheTin was the year when the two individuals in question were consul]]. (During UsefulNotes/JuliusCaesar's first consulate in 59 BCE, his co-consul Bibulus was so unpopular and so thoroughly stymied in his first attempt to seriously exercise consular power early in the year[[note]]Within a month of their taking office, Caesar had called a vote of the Plebeian Assembly on his signature piece of legislation, a land reform bill. Bibulus showed up to the assembly to veto the vote, but the crowd attacked him and dumped feces on his head, at which point Bibulus and his conservative supporters (including Cato) departed. Bibulus claimed that he was vetoing the proceedings the entire time, but Caesar claimed that even if Bibulus had been doing that, neither he nor anyone else could hear him over the roar of the crowd. Bibulus was unpopular enough (and Caesar popular enough) that we really can't tell what actually happened. It also raised a question of Roman law which the Romans never got around to answering--is a consul's veto effective when the consul issues it or when it is received and understood by the official whose actions are being vetoed?[[/note]] that he retreated to his house for the rest of his term; this left the field solely to Caesar, and people jokingly started to call 59 BCE "the year of Julius and Caesar being consul.") The consular-year naming continued after Augustus overthrew the Republic and established the Principate form of the Empire (in which the Republic nominally still ran like it used to and the Emperor was JustTheFirstCitizen). However, after the Crisis of the Third Century, Diocletian's Dominate (basically the Empire saying, "why yes the Emperor is a king"), regnal years came back into use. When the Romans had to use a continuously-numbered calendar (e.g. in histories), they counted years from the foundation of the city of Rome -- ''AbUrbeCondita'' or A.V.C.

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*** At some point, the Romans decided that this business of having unassigne time wasn't on for whatever reason. This time was thus divided into two new months at the end of the year, ''Ianuarius'' (Opening or Janus's) and ''Februarius'' (Purification, referring to a winter festival). This change is attributed to Numa Pompilius, the legendary second king of Rome.

* GMT Midnight on January 1, 1970, was chosen as "Second 0" to define the UNIX epoch. It was picked arbitrarily and not expected to be around for long, especially since we are going to run out of digits on January 19, 2038 (at 03:14:07 UTC), using the original method of storing that time (count one per second since the epoch: simple as can be; it's just they didn't anticipate UNIX surviving for over 2.1 billion seconds -- the amount of seconds needed to go through 31 bits). Some newer systems have tried to fix this by doubling the size of the field used to store this information, so that the calendar will still work for eons and eons.

* The German RPG ''Das schwarze Auge'' (VideoGame/RealmsOfArkania) had the main realm count the years by the current Emperor. By now reckoning has been changed (back) to the 'BF - Fall of Bosparan' reckoning, counting from the fall of the former empire. There are also numerous other calendars around in that world, counting from the first landing of gildenland settlers, the independence of countries, the threat of a catastrophe by a messenger of the gods to a city, and so on.

*** Though it should be noted that B.C.E./C.E. actually were religions to begin with, meaning Before Christian Era and Christian Era.

* Chinese emperors had a tendency to declare a new era every few years, a practice dating back to the Han Dynasty and lasting up to the Ming Dynasty when it was replaced by a system with one era per emperor. This practice was also adopted by the Japanese, where it lasted until the Meiji Restoration.

* Midnight on January 1, 1970, was chosen as "Second 0" to define the UNIX epoch. It was picked arbitrarily and not expected to be around for long, especially since we are going to run out of digits on January 19, 2038 (at 03:14:07 UTC), using the original method of storing that time (count one per second since the epoch: simple as can be; it's just they didn't anticipate UNIX surviving for over 2.1 billion seconds -- the amount of seconds needed to go through 31 bits). Some newer systems have tried to fix this by doubling the size of the field used to store this information, so that the calendar will still work for eons and eons.

* ''TabletopGame/EclipsePhase'' uses AF (after the Fall), mostly as a way to avert ExtyYearsFromNow. ("The Fall" being when a bunch of crazy [=AIs=] nearly wiped humanity out.)

* In ''Franchise/AvatarTheLastAirbender'', the calendar reset with the Air Nomad Genocide starting the Hundred Year War. Times before the war are BG (Before [[FinalSolution Genocide]]) and times during and after the war are AG (After Genocide).

** Both ''Legends'' and the current ''Franchise/StarWarsExpandedUniverse'' give us a lot of various calendars, which when you're talking about a galaxy-wide civilization across over 35,000 years of history, millions of planets and quadrillions of beings, makes sense. You've got the Tho Yor Arrival calendar, dating from when the first arks brought the pilgrims to Tython that would eventually found the Jedi Knights roughly 35,000 years before the movies, then you've got the Republic Year calendar dating from when the Galactic Republic was founded (roughly 25,000 years before the movies), the Tapani Calendar (started roughly 12,000 years before the films, used in one sector dating to when settlers first arrived there, and using a different length of year localized to the area), the After the Treaty of Coruscant dating to the treaty that set in motion the events of the ''VideoGame/StarWarsTheOldRepublic'' MMO, plus the Great Resynchronization calendar, an in-universe attempt to create a new standard calendar to cut through the variety of calendars in use (it puts Year Zero as 3 years before [[Film/ThePhantomMenace Episode I]]), and the Imperial Year dating to Palpatine's declaration of a New order in [[Film/RevengeOfTheSith Episode III]], and lastly the Before the Battle of Yavin/After the Battle of Yavin calendar dating to the events of Star Wars: A New Hope, which is taking the calendar most widely used by fans and making it an in-universe calendar. It's a lot of systems, but it's a big galaxy with a lot of history.

* The main setting's calendar has gone through several iterations, with setting books pointedly avoiding giving specific timeframes for most of them in order to preserve Storyteller's freedom. It was initially measured in years pertaining to the Age of Man, when the Primordials were overthrown and the Solar Deliberative was established. When the Solar Deliberative fell during the Usurpation, the Shogunate fiddled with an alternate calendar. At least until the Great Contagion ruined that as well and the Scarlet Empress ended up unifying various daimyos into the Realm, which is why the calendar currently uses RY (Realm Year) to designate how many years it's been since she took the throne. The end result is a calendar system that basically says, "It has been [[XDaysSince X years since]] the last world-shaking cataclysm."

* ''TabletopGame/{{Exalted}}'' had its timeline initially measured in years pertaining to the Age of Man, when the Primordials were overthrown and the Solar Deliberative was established. When the Solar Deliberative fell during the Usurpation, the Shogunate fiddled with an alternate calendar. At least until the Great Contagion fucked with ''that'' and the Scarlet Empress ended up unifying various daimyos into the Realm, which is why the calendar currently uses RY (Realm Year) to designate how many years it's been since she took the throne.
** The calendar system basically says, "It has been [[XDaysSince X years since]] the last world-shaking cataclysm."
*** It says something when the calendar used by Autochthonia (which started somewhere in the days of the Solar Deliberative and hasn't been reset since) has a current date that's ''several thousand years'' farther along than the one currently used in Creation.

** Played straight in the Dark Imperium era. After the Primarch returned and took over the Imperium, he found out that not only had recent events caused a serious TimeyWimeyBall effect on the last few centuries, ten thousand years of flawed record keeping and deliberate redactions meant that current date even on Terra itself had a margin of error of ''a thousand years'' in either direction. He ended up just giving up and declaring that the new calendar would start from when the new Warp Storm visible in the sky of every world first appeared there and count in local years. It's less precise and requires constant conversions, but it's a hell of a lot more accurate.

* In general, this is the case. It took a long time for people to discover that a "year" took approximately 365 days. Eventually it was discovered to be closer to 365.25. This means that every 4th year of the calendar will contain a leap day added to February to make up the difference and thus the year will be called a leap year. In modern times, it was narrowed down to 365.2425. This means that every 100th year, that year will not be a leap year and not contain a leap day, except every 400th year WILL be a leap year. This works almost perfectly except for the fact that the length of a year has slowly been changing for all of Earth's history (as does the length of a day thanks to the moon slowing down the Earth's rotation). For the purposes of the modern Gregorian calendar, with the invention of atomic clocks and exact measuring systems, we can make changes to the calendar without causing the aforementioned Shakespean paradox where two people can die on the "same day" despite having died actual days apart from each other. This also makes it simpler for lay people as they don't need complex math to figure out the year while the scientists who use complex math anyways can figure it out for us. Even as science, religion, and politics became more and more separated, the Gregorian calendar has stayed more or less intact because it would be too confusing and controversial to switch over to something new (which is also one of the reasons why other cultures refuse to give up their own calendars and also to thumb their noses at the church as Isaac Asimov claimed).

* The Franchise/{{Gundam}} franchise loves using alternate calendar systems, but the only one that really matches this trope is ''[[Anime/AfterWarGundamX Gundam X]]'', which is set in '''A'''fter '''W'''ar 0015, 15 years after the [[ApocalypseHow disastrous end of the 7th Space War]] which wiped out 99% of humanity living on Earth. Some fan theories suggest that ''[[Anime/MobileSuitGundamWing Gundam Wing]]''[='s=] '''A'''fter '''C'''olony calendar started with the launch of Skylab, but there isn't any official proof that this is true or not. Special mention to ''Anime/TurnAGundam'', which implicitly has several dozen calendar changes in its backstory, to the point where this trope is the only explanation.

* One of the proofs that the Holy Britannian Empire is ''the'' most dominant force on Earth in Anime/CodeGeass universe, the calendar doesn't follow the real world AD/CE - instead, we have A.T.B, for "Ascension to Throne, Britannia", counting from the establishment of the first Celtic King in the Britannian royal line, rather than the birth of Christ. Closer to this trope is the Revolutionary Calendar used by the EU, a variant of the French Republican Calendar that sets its first year to 1790, the year after the French Revolution.

** Speaking of the Universal Century, ''Anime/MobileSuitGundamUnicorn'' reveals that the calendar change occurred on the eve of the United Nations' reformation into the [[TheFederation Earth Federation]], which was supposed to be peaceful... were it not for a GovernmentConspiracy blowing up the Laplace space station where the first Prime Minister of the Federation was holding his inauguration speech, an event whose aftershocks shaped world history for the next hundred years.

** The last big change to Roman time was the Julian reform. The Roman calendar before UsefulNotes/JuliusCaesar was a lunisolar one where each month roughly corresponded to one cycle of phases of the Moon. The advantage of the weird original Roman calendar with about 2 months' worth of time not actually part of any month was that it always aligned with the solar year; after December ended, the Romans of those days waited for the next vernal equinox to start the next year's ''Martius''. The addition of ''Ianuarius'' and ''Februarius'' created a headache in that now that a year was supposed to be 12 months, it would start falling behind the actual seasons, and fairly quickly at that (12 lunar cycles comes to about 354 days, 11 days less than a solar year). As a result, the Romans added an extra "intercalary" month would be added to make the year line up with the seasons when the Pontifex Maximus (the chief priest of the Roman state) determined it was needed every 2-3 years.\\

** The Romans did not usually use a continuous numbering system for their years, the way we do. Unique years were identified with reference to the political leadership of the state. Under the monarchy, this meant regnal years (the Xth year of King Y's reign). Under the Republic, they referred to the years as "[the year] ''X'' and ''Y'' being consul," which, naturally, [[ExactlyWhatItSaysOnTheTin was the year when the two individuals in question were consul]]. (During UsefulNotes/JuliusCaesar's first consulate in 59 BCE, his co-consul Bibulus was so unpopular and so thoroughly stymied in his first attempt to seriously exercise consular power early in the year[[note]]Within a month of their taking office, Caesar had called a vote of the Plebeian Assembly on his signature piece of legislation, a land reform bill. Bibulus showed up to the assembly to veto the vote, but the crowd attacked him and dumped feces on his head, at which point Bibulus and his conservative supporters (including Cato) departed. Bibulus claimed that he was vetoing the proceedings the entire time, but Caesar claimed that even if Bibulus had been doing that, neither he nor anyone else could hear him over the roar of the crowd. Bibulus was unpopular enough (and Caesar popular enough) that we really can't tell what actually happened.[[/note]] that he retreated to his house for the rest of his term; this left the field solely to Caesar, and people jokingly started to call 59 BCE "the year of Julius and Caesar being consul.") The consular-year naming continued after Augustus overthrew the Republic and established the Principate form of the Empire (in which the Republic nominally still ran like it used to and the Emperor was JustTheFirstCitizen). However, after the Crisis of the Third Century, Diocletian's Dominate (basically the Empire saying, "why yes the Emperor is a king"), regnal years came back into use. When the Romans had to use a continuously-numbered calendar (e.g. in histories), they counted years from the foundation of the city of Rome -- ''AbUrbeCondita'' or A.V.C.

Caesar found what he was looking for in Egypt. While chasing Pompey around the Eastern Mediterranean, he encountered the Ancient Egyptian calendar, which ignored the Moon completely and simply made every month 30 days long, with an additional 5 days belonging to no month as a kind of festival time at the end of the year. Caesar liked this system, although he had two problems with it: it still meant the dates would get out of line with the seasons, albeit at a much slower rate,[[note]]The Egyptians knew this, but didn't care as much because of some religious stuff they had about the first rising of Sirius, plus the problem fixed itself every 1,460 years, which the Egyptians were OK with it seems.[[/note]] and the concept of days with no month annoyed him for some reason. To address the first problem, he added a sixth additional day to the year every fourth year (which one of the Ptolemaic Greek Kings of Egypt had tried to do about 200 years earlier, but the Egyptians had resisted for the aforementioned religious reasons, and probably also as a way of thumbing their noses at the Greeks). To address the second problem, the six days were distributed among the months of the year. To commemorate these changes, Caesar then renamed ''Quintilis'', the month in which he had been born, ''Iulius'' after himself. Augustus would then rename the following month ''Augustus'' after himself to commemorate the [[http://en.wikipedia.org/wiki/Battle_of_Actium Battle of Actium]].