Changes

In the year-period system, which is still the official year-dating system in Japan, the imperial court determines that the era name (''nengô'' 年号) shall be changed to XX,  a two-character name using Chinese (on) readings  such as Tai-ka  大化 or Hei-sei 平成. (From 749-770 four-character names were used.) The beginnings of eras are given in reference books; there is also a list in the article on [[Japanese Eras]]. This change in name can occur at any time of year.  

In the year-period system, which is still the official year-dating system in Japan, the imperial court determines that the era name (''nengô'' 年号) shall be changed to XX,  a two-character name using Chinese (on) readings  such as Tai-ka  大化 or Hei-sei 平成. (From 749-770 four-character names were used.) The beginnings of eras are given in reference books; there is also a list in the article on [[Japanese Eras]]. This change in name can occur at any time of year.  

In China, the first year period, Jian-yuan (Kengen) 建元, started in 140 A.D.  In Japan, the first was Taika 大化 in [[645]] A.D., and the first period change was occasioned in [[650]] by the court's receiving the gift of a white pheasant:  the period name was changed to Hakuchi 白雉. <ref>''Sources of Japanese Tradition'', Columbia University Press, 1:69, 76. </ref> After this, there were several decades when the names were not settled and the reign-year system was also used, but since [[701]] (Taihô), the eras have been reasonably established.  

In China, the first year period, Jian-yuan (Kengen) 建元, started in 140 A.D.  In Japan, the first was Taika 大化 in [[645]] A.D., and the first period change was occasioned in [[650]] by the court's receiving the gift of a white pheasant:  the period name was changed to Hakuchi 白雉. <ref>''Sources of Japanese Tradition'', Columbia University Press, 1:69, 76. </ref> After this, there were several decades when nengô were not used, except for a few months in 686, but since 701 (Taihô), the eras have been regularly established.  

In the period from 1336-1392 there were [[Nanboku-cho|two rival courts]]. Since the court determines the year periods, there were two sets of era names during this time.  In 1910 it was officially decided that, the "southern" court had been the legitimate court during the period,<ref> Ivan Morris, ''[[The Nobility of Failure]]'', p. 387. </ref> so the "southern" era names are the official ones given in lists. However, as the "northern" era names  were the ones actually used in most of the country, they are normally given somewhere in the lists, often marked as "northern dynasty."

In the period from 1336-1392 there were [[Nanboku-cho|two rival courts]]. Since the court determines the year periods, there were two sets of era names during this time.  In 1910 it was officially decided that, the "southern" court had been the legitimate court during the period,<ref> Ivan Morris, ''[[The Nobility of Failure]]'', p. 387. </ref> so the "southern" era names are the official ones given in lists. However, as the "northern" era names  were the ones actually used in most of the country, they are normally given somewhere in the lists, often marked as "northern dynasty."

===Start of an Era===

===Start of an Era===

The start of a new era could be declared for any number of reasons. Among them were the occurrence of the first or 58th year of the 60-year cycle (see below), a new emperor (usually sometime during the year after the death of the previous emperor), natural disasters, etc. Many periods were only three or four years long.  For most of history, the names had nothing to do with that of the emperor; though there was a Tenshô period, there was no "Emperor Tenshô." Furthermore, a change of emperor did not necessarily mean a new period.  However, since the start of the Meiji period (1868), the only reason for a new period has been the reign of a new emperor,<ref>This was made official in 1979.</ref> and the emperor is after death referred to by the name of the period he reigned in, so now we refer to the emperors Meiji, Taishô, and Shôwa.  However, unlike the ancient reign-year system, the new era starts on the day of the death of the previous emperor (Taishô period, Shôwa period), or on the day after (Heisei period), not from the next year.

The start of a new era could be declared for any number of reasons. The principle reason was the ascension of a new emperor (dai-hamjime 代始め). Throughout most of history it was normal to proclaim the new era during the year following the actual ascension. A very late or no dai-hajime nengô often seems to indicate some type of power struggle. This is particularly noticeable in the 17th century when the Edo shogunate was trying to dominate the imperial court. Among other reasons for a new nengô were the occurrence of the first or 58th year of the 60-year cycle (see below), a felicitous omen (especially in the early period), disasters, etc.   Many periods were only three or four years long.  For most of history, the names had nothing to do with that of the emperor: though there was a Tenshô period, there was no "Emperor Tenshô." However, since the start of the Meiji period (1868), the only reason for a new period has been the reign of a new emperor, and the emperor is after death referred to by the name of the period he reigned in, so now we refer to the emperors Meiji, Taishô, and Shôwa.  However, unlike the ancient reign-year system, the first year of new era starts on the day of the death of the previous emperor (Taishô period, Shôwa period), or on the day after (Heisei period), not the following year.

As mentioned above, a change in the era name can occur at any time of year.  For instance, the Tenshô Era began the 28th day of the Seventh Month of 1573 and lasted until the 8th day of the Twelfth Month of 1592.  New periods began during the day. However, the present period, Heisei 平成, began at exactly at midnight the morning of January 8, 1989.  The exact day an era begins was not considered important until recently, however. At times, as in the Edo period, eras were treated as having started at the beginning of the year retroactively.  Furthermore, as one never knows when a new period will begin, one often finds dates that officially did not exist. For example, there is a grave in western Tokyo (formerly  [[Musashi province]] ) dated  "Shitoku 4 (1387), 11th month," though Shitoku had ended in the 8th month. (Note that this is a "northern" ''nengô''.) In modern times, drivers licenses valid to "Shôwa 66" remained valid to 1991, though Shôwa ended in 1989.

As mentioned above, a change in the era name can occur at any time of year.  For instance, the Tenshô Era began the 28th day of the Seventh Month of 1573 and lasted until the 8th day of the Twelfth Month of 1592.  New periods began during the day. However, the present period, Heisei 平成, began at exactly at midnight the morning of January 8, 1989.  The exact day an era begins was not considered important until recently, however. At times, as in the Edo period, eras were treated as having started at the beginning of the year retroactively.  Furthermore, as one never knows when a new period will begin, one often finds dates that officially did not exist. For example, there is a grave in western Tokyo (formerly  [[Musashi province]] ) dated  "Shitoku 4 (1387), 11th month," though Shitoku had ended in the 8th month. (Note that this is a "northern" ''nengô''.) In modern times, drivers licenses valid to "Shôwa 66" remained valid to 1991, though Shôwa ended in 1989.

The first year of an era is called "gan-nen" 元年.  Subsequent years are counted from the beginning of the calendar year.  For example, the Shôwa period started December 25, 1926, and the second year of Shôwa 昭和二年 started one week later on January 1, 1927.  When calculating between year periods and the Western year, remember that the first year of the era is 1, not 0.  So, to calculate the dates of Shôwa, which began in 1926, add or subtract 1925 (=1926-1). Thus 1945 was 1945-1925 = Shôwa 20,  while Shôwa 34 was 1925+34 = 1959. For a list of eras and the years they began, see  the article on [[Japanese Eras]].

The first year of an era is called "gan-nen" 元年.  Subsequent years are counted from the beginning of the calendar year.  For example, the Shôwa period started December 25, 1926, and the second year of Shôwa 昭和二年 started one week later on January 1, 1927.  When calculating between year periods and the Western year, remember that the first year of the era is 1, not 0.  So, to calculate the dates of Shôwa, which began in 1926, add or subtract 1925 (=1926-1). Thus 1945 was 1945-1925 = Shôwa 20,  while Shôwa 34 was 1925+34 = 1959. For a list of eras and the years they began, see  the article on [[Japanese Eras]].

Dating using ''nengô'' is very settled in Japan, so there is no confusion about interpreting them in Japanese.  

Dating using ''nengô'' is very settled in Japan, so there is no confusion about the years they refer to.

==Cyclic, or ''Kanshi'' 干支, system==

==Cyclic, or ''Kanshi'' 干支, system==