The Japanese era name (年号, nengō, "year name"), also known as gengō (元号), is the first of the two elements that identify years in the Japanese era calendar scheme. The second element is a number which indicates the year number within the era (with the first year being "gan (元)"), followed by the literal "nen (年)" meaning "year".
Era names originated in 140 BCE in China, during the reign of the Emperor Wu of Han. As elsewhere in East Asia, the use of era names was originally derived from Chinese imperial practice, although the Japanese system is independent of the Chinese, Korean, and Vietnamese era-naming systems. Unlike these other similar systems, Japanese era names are still in use. Government offices usually require era names and years for official papers.
The five era names used since the end of the Edo period in 1868 can be abbreviated by taking the first letter of their romanized names. For example, S55 means Shōwa 55 (i.e. 1980), and H22 stands for Heisei 22 (2010). At 62 years and 2 weeks, Shōwa is the longest era to date.
The current era is Reiwa (令和), which began on 1 May 2019, following the 31st (and final) year of the Heisei era (平成31年). While the Heisei era (平成) started on the day after the death of the Emperor Hirohito (8 January 1989), the Reiwa era (令和) began the day after the planned and voluntary abdication of the 125th Emperor Akihito. Emperor Akihito received special one-time permission to abdicate, rather than serving in his role until his death, as is the rule. His elder son, Naruhito, ascended to the throne as the 126th Emperor of Japan on 1 May 2019.
|A graphical timeline is available at|
Timeline of Japanese era names
The system on which the Japanese era names are based originated in China in 140 BC, and was adopted by Japan in 645 CE, during the reign of Emperor Kōtoku.
The first era name to be assigned was "Taika" (大化), celebrating the political and organizational changes which were to flow from the great Taika reform (大化の改新) of 645. Although the regular practice of proclaiming successive era names was interrupted in the late seventh century, it was permanently re-adopted in 701 during the reign of Emperor Monmu (697–707). Since then, era names have been used continuously up through the present day.
Prior to the Meiji period, era names were decided by court officials and were subjected to frequent change. A new era name was usually proclaimed within a year or two after the ascension of a new emperor. A new era name was also often designated on the first, fifth and 58th years of the sexagenary cycle, because they were inauspicious years in Onmyōdō. These three years are respectively known as kakurei, kakuun, and kakumei, and collectively known as sankaku. Era names were also changed due to other felicitous events or natural disasters.
In historical practice, the first day of a nengō (元年, gannen) starts whenever the emperor chooses; and the first year continues until the next lunar new year, which is understood to be the start of the nengō's second year.
Era names indicate the various reasons for their adoption. For instance, the nengō Wadō (和銅), during the Nara period, was declared due to the discovery of copper deposits in Chichibu. Most nengō are composed of two kanji, except for a short time during the Nara period when four-kanji names were sometimes adopted to follow the Chinese trend. Tenpyō Kanpō (天平感宝), Tenpyō Shōhō (天平勝宝), Tenpyō Hōji (天平宝字) and Tenpyō Jingo (天平神護) are some famous nengō names that use four characters. Since the Heian period, Confucian thoughts and ideas have been reflected in era names, such as Daidō (大同), Kōnin (弘仁) and Tenchō (天長). Although there currently exist a total of 248 Japanese era names, only 73 kanji have been used in composing them. Out of these 73 kanji, 31 of them have been used only once, while the rest have been used repeatedly in different combinations.
Nengō in modern Japan
Mutsuhito assumed the throne in 1867, during the third year of the Keiō (慶応) era. On 23 October 1868, the era name was changed to "Meiji" (明治), and a "one reign, one era name" (一世一元, issei-ichigen) system was adopted, wherein era names would change only upon immediate imperial succession. This system is similar to the now-defunct Chinese system used since the days of the Ming dynasty. The Japanese nengō system differs from Chinese practice, in that in the Chinese system the era name was not updated until the year following the emperor's death.
In modern practice, the first year of a nengō (元年, gannen) starts immediately upon the emperor's accession and ends on 31 December. Subsequent years follow the Gregorian calendar. For example, the Meiji era lasted until 30 July 1912, when the Emperor died and the Taishō (大正) era was proclaimed. 1912 is therefore known as both "Meiji 45" and "Taishō 1" (大正元年, Taishō gannen), although Meiji technically ended on 30 July with Mutsuhito's death.
This practice, implemented successfully since the days of Meiji but never formalized, became law in 1979 with the passage of the Era Name Law (元号法, gengō-hō). Thus, since 1868, there have only been five era names assigned: Meiji, Taishō, Shōwa, Heisei, and Reiwa, each corresponding with the rule of only one emperor. Upon death, the emperor is thereafter referred to by the era of his reign. For example, Mutsuhito is posthumously known as "Emperor Meiji" (明治天皇, Meiji Tennō).
It is protocol in Japan that the reigning emperor be referred to as Tennō Heika (天皇陛下, "His Imperial Majesty the Emperor") or Kinjō Tennō (今上天皇, "current emperor"). To call the current emperor by the current era name, i.e. "Reiwa", even in English, is a faux pas, as this is — and will be — his posthumous name. Use of the emperor's given name (i.e., "Naruhito") is rare, and is considered vulgar behaviour in Japanese.
Periods without era names
The era name system that was introduced by Emperor Kōtoku was abandoned after his death; no era names were designated between 654 and 686. The system was briefly reinstated by Emperor Tenmu in 686, but was again abandoned upon his death about two months later. In 701, Emperor Monmu once again reinstated the era name system, and it has continued uninterrupted through today.
Although use of the Gregorian calendar for historical dates became increasingly common in Japan, the traditional Japanese system demands that dates be written in reference to era names. The apparent problem introduced by the lack of era names was resolved by identifying the years of an imperial reign as a period.
Although in modern Japan posthumous imperial names correspond with the eras of their reign, this is a relatively recent concept, introduced in practice during the Meiji period and instituted by law in 1979. Therefore, the posthumous names of the emperors and empresses who reigned prior to 1868 may not be taken as era names by themselves. For example, the year 572—the year in which Emperor Bidatsu assumed the Chrysanthemum Throne – is properly written as "敏達天皇元年" (Bidatsu-Tennō Gannen, "the first year of Emperor Bidatsu"), and not "敏達元年" (Bidatsu Gannen, "the first year of Bidatsu"), although it may be abbreviated as such. By incorporating both proper era names and posthumous imperial names in this manner, it is possible to extend the nengō system to cover all dates from 660 BC through today.
Unofficial era name system
In addition to the official era name system, in which the era names are selected by the imperial court, one also observes—primarily in the ancient documents and epigraphs of shrines and temples—unofficial era names called shinengō (私年号, "personal era name"), also known as ginengō (偽年号) or inengō (異年号). Currently, there are over 40 confirmed shinengō, most of them dating from the middle ages. Shinengō used prior to the reestablishment of the era name system in 701 are usually called itsunengō (逸年号).[a]
Because official records of shinengō are lacking, the range of dates to which they apply is often unclear. For example, the well-known itsunengō Hakuhō (白鳳) is normally said to refer to 650–654 CE; a poetic synonym for the Hakuchi era. However, alternate interpretations exist. For example, in the Nichūreki, Hakuhō refers to 661–683 CE, and in some medieval temple documents, Hakuhō refers to 672–685 CE. Thus, shinengō may be used as an alternative way of dating periods for which there is no official era name.
Other well-known itsunengō and shinengō include Hōkō (法興) (591–621+ CE), Suzaku (朱雀) (686), Fukutoku (福徳) (1489–1492), Miroku (弥勒) (1506–1507 or 1507–1509) and Meiroku (命禄) (1540–1543).
The most recent shinengō is Seiro (征露) (1904–1905), named for the Russo-Japanese War.
Edo period scholar Tsurumine Shigenobu proposed that Kyūshū nengō (九州年号), said to have been used in ancient Kumaso, should also be considered a form of shinengō. This claim is not generally recognized by the academic community. Lists of the proposed Kyūshū nengō can be seen in the Japanese language entries 鶴峯戊申 and 九州王朝説.
Certain era names have specific characters assigned to them, for instance ㋿ for the Reiwa period, which can also be written as 令和. These are included in Unicode: Code points U+32FF (㋿), U+337B (㍻), U+337C (㍼), U+337D (㍽) and U+337E (㍾) are used for the Reiwa, Heisei, Shōwa, Taishō and Meiji eras, respectively.
Certain calendar libraries support the conversion from and to the era system, as well as rendering of dates using it.
Support for the new era in Japanese imperial transition of 2019
Computers and software manufacturers needed to test their systems in preparation for the new era which began on 1 May 2019. Windows provided a test mechanism to simulate a new era ahead of time. Java Development Kit 11 supported this era using the placeholders "元号" for Japanese, "NewEra" for other languages. The final name was added in JDK 12.0.1, after it was announced by the Japanese government.
The list of Japanese era names is the result of a periodization system which was established by Emperor Kōtoku in 645. The system of Japanese era names (年号, nengō, "year name") was irregular until the beginning of the 8th century. After 701, sequential era names developed without interruption across a span of centuries. As of April 1, 2019, there have been 239 era names.
|Name of era||Notes|
|Asuka period (538–710)|
|498||Earliest date for which recorded shi-nengō are identified; "Unofficial nengō system" section below|
|645||大化||Taika||Emperor Kōtoku, 645–654.|
|654||Era not named; see "Non-Nengō periods" section below|
|686||朱鳥||Shuchō||also Suchō, Akamitori or Akamidori; Emperor Tenmu, 672–686.|
|686||Era not named; see "Non-Nengō periods" section below|
|701||大宝||Taihō||also Daihō; Emperor Monmu, 697–707.|
|704||慶雲||Keiun||also Kyōun; Empress Genmei, 707–715.|
|Nara period (710–794)|
|715||霊亀||Reiki||Empress Genshō, 715–724.|
|724||���亀||Jinki||also Shinki; Emperor Shōmu, 724–749.|
|729||天平||Tenpyō||also Tenbyō or Tenhei|
|749||天平勝宝||Tenpyō-shōhō||also Tenbyō-shōbō or Tenpei-shōhō; Empress Kōken, 749–758.|
|757||天平宝字||Tenpyō-hōji||also Tenbyō-hōji or Tenpei-hōji; Emperor Junnin, 758–764; Empress Shōtoku, 764–770.|
|765||天平神護||Tenpyō-jingo||also Tenbyō-jingo or Tenhei-jingo|
|770||宝亀||Hōki||Emperor Kōnin, 770–781.|
|781||天応||Ten'ō||Emperor Kanmu, 781–806.|
|Heian period (794–1185)|
|806||大同||Daidō||Emperor Heizei, 806–809; Emperor Saga, 809–823.|
|810||弘仁||Kōnin||Emperor Junna, 823–833.|
|824||天長||Tenchō||Emperor Ninmyō, 833–850.|
|834||承和||Jōwa||also Shōwa or Sōwa|
|848||嘉祥||Kashō||also Kajō; Emperor Montoku, 850–858.|
|857||天安||Ten'an||also Tennan; Emperor Seiwa, 858–876.|
|859||貞観||J��gan||Emperor Yōzei, 876–884.|
|877||元慶||Gangyō||also Gankyō or Genkei; Emperor Kōkō, 884–887.|
|885||仁和||Ninna||also Ninwa; Emperor Uda, 887–897.|
|889||寛平||Kanpyō||also Kanpei or Kanbyō or Kanbei or Kanhei; Emperor Daigo, 887–930.|
|923||延長||Enchō||Emperor Suzaku, 930–946.|
|938||天慶||Tengyō||also Tenkei or Tenkyō; Emperor Murakami, 946–967.|
|964||康保||Kōhō||Emperor Reizei, 967–969.|
|968||安和||Anna||also Anwa; Emperor En'yū, 969–984.|
|983||永観||Eikan||also Yōkan; Emperor Kazan, 984–986.|
|985||寛和||Kanna||also Kanwa; Emperor Ichijō, 986–1011.|
|990||正暦||Shōryaku||also Jōryaku or Shōreki|
|1004||寛弘||Kankō||Emperor Sanjō, 1011–1016.|
|1012||長和||Chōwa||Emperor Go-Ichijō, 1016–1036.|
|1028||長元||Chōgen||Emperor Go-Suzaku, 1036–1045.|
|1044||寛徳||Kantoku||Emperor Go-Reizei, 1045–1068.|
|1046||永承||Eishō||also Eijō or Yōjō|
|1069||延久||Enkyū||Emperor Go-Sanjō, 1068–1073.|
|1074||承保||Jōhō||also Shōhō or Shōho; Emperor Shirakawa, 1073–1086.|
|1077||承暦||Jōryaku||also Shōryaku or Shōreki|
|1087||寛治||Kanji||Emperor Horikawa, 1087–1107.|
|1106||嘉承||Kajō||also Kashō or Kasō; Emperor Toba, 1107–1123.|
|1120||保安||Hōan||Emperor Sutoku, 1123–1142.|
|1142||康治||Kōji||Emperor Konoe, 1142–1155.|
|1151||仁平||Ninpei||also Ninpyō or Ninbyō or Ninhyō or Ninhei|
|1154||久寿||Kyūju||Emperor Go-Shirakawa, 1155–1158.|
|1156||保元||Hōgen||also Hogen; Emperor Nijō, 1158–1165.|
|1165||永万||Eiman||also Yōman; Emperor Rokujō, 1165–1168.|
|1166||仁安||Nin'an||also Ninnan; Emperor Takakura, 1168–1180.|
|1177||治承||Jishō||also Jijō or Chishō; Emperor Antoku, 1180–1185.|
|1182||寿永||Juei||Emperor Go-Toba, 1183–1198.|
|Kamakura period (1185–1333)|
|1190||建久||Kenkyū||Emperor Tsuchimikado, 1198–1210.|
|1207||承元||Jōgen||also Shōgen; Emperor Juntoku, 1210–1221.|
|1219||承久||Jōkyū||also Shōkyū; Emperor Chūkyō, 1221. Emperor Go-Horikawa, 1221–1232.|
|1232||貞永||Jōei||also Teiei; Emperor Shijō, 1232–1242.|
|1234||文暦||Bunryaku||also Monryaku or Monreki or Bunreki|
|1240||仁治||Ninji||also Ninchi; Emperor Go-Saga, 1242–1246.|
|1243||寛元||Kangen||Emperor Go-Fukakusa, 1246–1260.|
|1256||康元||Kōgen||Emperor Kameyama, 1260–1274.|
|1264||文永||Bun'ei||Emperor Go-Uda, 1274–1287.|
|1278||弘安||Kōan||Emperor Fushimi, 1287–1298.|
|1293||永仁||Einin||Emperor Go-Fushimi, 1298–1301.|
|1299||正安||Shōan||Emperor Go-Nijō, 1301–1308.|
|1308||延慶||Enkyō||also Engyō or Enkei; Emperor Hanazono, 1308–1318.|
|1317||文保||Bunpō||also Bunhō; Emperor Go-Daigo, 1318–1339.|
|Nanboku-chō period (1334–1392)|
|1384||元中||Genchū||Genchū 9 becomes Meitoku 3 in post Nanboku-chō reunification|
|1384||至徳||Shitoku||also Meitoku or Sitoku|
|1390||明徳||Meitoku||Meitoku 3 replaces Genchū 9 in post-Nanboku-chō reunification|
|Muromachi period (1392–1573)|
|1394||応永||Ōei||Emperor Shōkō, 1412–1428.|
|1428||正長||Shōchō||Emperor Go-Hanazono, 1428–1464.|
|1460||寛正||Kanshō||Emperor Go-Tsuchimikado, 1464–1500.|
|1492||明応||Meiō||also Myōō; Emperor Go-Kashiwabara, 1500–1526.|
|1521||大永||Daiei||Emperor Go-Nara, 1526–1557.|
|1555||弘治||Kōji||Emperor Ōgimachi, 1557–1586.|
|Azuchi-Momoyama period (1573–1603)|
|1573||天正||Tenshō||Emperor Go-Yōzei, 1586–1611.|
|1596||慶長||Keichō||also Kyōchō; Emperor Go-Mizunoo, 1611–1629.|
|Edo period (1603–1868)|
|1624||寛���||Kan'ei||Empress Meishō, 1629–1643; Emperor Go-Kōmyō, 1643–1654.|
|1652||承応||Jōō||also Shōō; Emperor Go-Sai, 1655–1663.|
|1655||明暦||Meireki||also Myōryaku or Meiryaku or Myōreki|
|1661||寛文||Kanbun||Emperor Reigen, 1663–1687.|
|1673||延宝||Enpō||also Enhō, formerly written 延寳|
|1684||貞享||Jōkyō||Emperor Higashiyama, 1687–1709.|
|1704||宝永||Hōei||Emperor Nakamikado, 1709–1735.|
|1716||享保||Kyōhō||Emperor Sakuramachi, 1735–1747.|
|1744||延享||Enkyō||Emperor Momozono, 1747–1762.|
|1751||宝暦||Hōreki||also Hōryaku; Empress Go-Sakuramachi, 1762–1771.|
|1764||明和||Meiwa||Emperor Go-Momozono, 1771–1779.|
|1772||安永||An'ei||Emperor Kōkaku, 1780–1817.|
|1804||文化||Bunka||also Monka; Emperor Ninkō, 1817–1846.|
|1844||弘化||Kōka||Emperor Kōmei, 1846–1867.|
|1865||慶応||Keiō||also Kyōō; Emperor Meiji, 1867–1868.|
|Modern Japan (from 1868)|
|1868||明治||Meiji||Emperor Meiji, 1868–1912.|
|1912||大正||Taishō||Emperor Taishō, 1912–1926.|
|1926||昭和||Shōwa||Emperor Shōwa, 1926–1989.|
- Reign of Emperor Jimmu, 660–581 BC
- Reign of Emperor Suizei, 581–548 BC
- Reign of Emperor Annei, 548–510 BC
- Reign of Emperor Itoku, 510–475 BC
- Reign of Emperor Kōshō, 475–392 BC
- Reign of Emperor Kōan, 392–290 BC
- Reign of Emperor Kōrei, 290–214 BC
- Reign of Emperor Kōgen, 214–157 BC
- Reign of Emperor Kaika, 157���97 BC
- Reign of Emperor Sujin, 97–29 BC
- Reign of Emperor Suinin, 29 BC–AD 71
- Reign of Emperor Keikō, AD 71–131
- Reign of Emperor Seimu, 131–192
- Reign of Emperor Chūai, 192–201
- Regency of Empress Jingū, 201–270
- Reign of Emperor Ōjin, 270–313
- Reign of Emperor Nintoku, 313–400
- Reign of Emperor Richū, 400–406
- Reign of Emperor Hanzei, 406–412
- Reign of Emperor Ingyō, 412–454
- Reign of Emperor Ankō, 454–457
- Reign of Emperor Yūryaku, 457–480
- Reign of Emperor Seinei, 480–485
- Reign of Emperor Kenzō, 485–488
- Reign of Emperor Ninken, 488–499
- Reign of Emperor Buretsu, 499–507
- Reign of Emperor Keitai, 507–534
- Reign of Emperor Ankan, 534–536
- Reign of Emperor Senka, 536–540
- Reign of Emperor Kinmei, 540–572
- Reign of Emperor Bidatsu, 572–586
- Reign of Emperor Yōmei, 586–588
- Reign of Emperor Sushun, 588–593
- Reign of Emperor Suiko, 593–629
- Reign of Emperor Jomei, 629–645
Post-Taika chronology intervals not covered by the nengō system include:
- Reign of Empress Saimei, 655–662 ... Saimei (period)
- Reign of Emperor Tenji, 662–672 ... Tenji (period)
- Reign of Emperor Kōbun, 672–673 ... Kōbun (period) or Sujaku (or Suzaku)
- Reign of Emperor Tenmu, 673–686 ... Tenmu (period) or Hakuhō period
- Reign of Empress Jitō, 687–697 ... Jitō (period)
- Reign of Emperor Monmu, 697–701 ... Monmu (period)
- Japanese calendar
- Japanese imperial year
- Jikkan Jūnishi (sexagenary cycle)
- Regnal name
- Regnal years worldwide
- A list of shinengō and more information can be seen in the Japanese language entry on 私年号.
- Lü, Zongli (2003). Power of the words: Chen prophecy in Chinese politics, AD 265-618. ISBN 9783906769561.
- Sogner, Sølvi (2001). Making Sense of Global History: The 19th International Congress of the Historical Sciences, Oslo 2000, Commemorative Volume. ISBN 9788215001067.
- "International Congress of Historical Sciences". International Congress of Historical Sciences. 19. 2000. Retrieved 29 December 2019.
- "Ancient tradition carries forward with Japan's new era". Retrieved 29 December 2019.
- Reiwa Nengō Announcement Footage, 1 April 2019
- Rich, Motoko (30 April 2019). "Emperor Akihito, Who Gave Japan's Monarchy a Human Face, Abdicates Throne". New York Times. Retrieved 30 April 2019.
- "天皇陛下 「生前退位」の意向示される ("His Majesty The Emperor Indicates His Intention to 'Abdicate'")" (in Japanese). NHK. 13 July 2016. Archived from the original on 13 July 2016. Retrieved 13 July 2016.
- "Japanese Emperor Akihito 'wishes to abdicate'". BBC News. 13 July 2016. Retrieved 17 July 2016.
- "Japan rings in new era as Naruhito becomes emperor". Al Jazeera. 30 April 2019. Retrieved 30 April 2019.
- Brown & Ishida (1979), p. 32.
- Ponsonby-Fane, Richard. (1956). Kyoto: the Old Capital of Japan, 794–1869, p. 321.
- Murray (1894) p. 402, citing Bramsen (1880) pp. 54–55.The year-periods (nengō) do not ordinarily overlap with the reigns of the early monarchs; and generally, a new one was chosen whenever it was deemed necessary to commemorate an auspicious or ward off a malign event.
- "The Japanese Calendar", National Diet Library, Japan
- "年号一覧" (in Japanese). Archived from the original on 19 October 2007.
- "JapaneseDate (Java Platform SE 8 )". Archived from the original on 15 May 2015.
- "The Japanese Calendar's Y2K Moment".
- "JDK 11 Release Notes, Important Changes, and Information". www.oracle.com. Retrieved 1 October 2018.
Japanese calendars, both in java.time.chrono and java.util packages support the upcoming Japanese new era, which will be in effect from May 1st, 2019. While the name of the era was yet to be known, placeholder names ("元号" for Japanese, "NewEra" for other languages) are provided for its display names. The placeholder names will be replaced with the legitimate era name, Reiwa, in a future update, thus applications should not depend on those placeholder names.
- Kishida, Naoki (14 July 2018). "Java 11 API Change Proposals". DZone Java. Retrieved 1 October 2018.
- Request to reserve the code point for square Japanese new era name (PDF), 19 December 2017
- The Japan National Body (23 May 2018), Update on SC2 N4577 "Request to reserve the code point for square Japanese new era name" (PDF)
- "RESOLUTION M 23-10", Resolutions of the 23rd ISO/IEC JTC 1/SC 2 Plenary Meeting, 28 June 2018
- Future Additions to ISO/IEC 10646 (January 2018) (PDF), 25 January 2018
- "Proposed New Characters: Pipeline Table". Unicode Consortium. 30 June 2018.
- Whistler, Ken (16 July 2018), Unicode 12.1 Planning Considerations
- Tsuchihashi (1952), p. 16.
- NengoCalc (645) 大化 Taika
- Brown & Ishida (1979) pp. 266–267; Varley (1980) pp. 132–133; Titsingh (1834) pp. 47–50
- NengoCalc (650) 白雉 Hakuchi
- Compare Nussbaum (2005) "Hakuhō" p. 280; "Hakuhou jidai". JAANUS (Japanese Architecture and Art Net Users System). 2001. Retrieved 24 January 2011.
- NengoCalc (686) 朱鳥 Suchō
- Brown & Ishida (1979) pp. 268–269; Varley (1980), pp. 135–136; Titsingh (1834) pp. 58–59
- NengoCalc (701) 大宝 Taihō
- Brown & Ishida (1979) pp. 270–271; Varley (1980), pp. 137–140; Titsingh (1834) pp. 60–63
- Brown & Ishida (1979) p. 271; Varley (1980), p. 140; Titsingh (1834) pp. 63–65
- Brown & Ishida (1979) pp. 271–272; Varley (1980), pp. 140–141; Titsingh (1834) pp. 65–67
- Brown & Ishida (1979) pp. 272–273; Varley (1980), pp. 141–143; Titsingh (1834) pp. 67–73
- Brown & Ishida (1979) pp. 274–275; Varley (1980), p. 143; Titsingh (1834) pp. 73–75
- Brown & Ishida (1979) p. 275; Varley (1980), pp. 143–144; Titsingh (1834) pp. 75–78
- Brown & Ishida (1979) p. 276; Varley (1980), pp. 144–147; Titsingh (1834) pp. 78–81
- Brown & Ishida (1979) pp. 276–277; Varley (1980), pp. 147–148; Titsingh (1834) pp. 81–85
- Brown & Ishida (1979) pp. 277–279; Varley (1980), pp. 148–150; Titsingh (1834) pp. 86–95
- Brown & Ishida (1979) pp. 279–280; Varley (1980), p. 151; Titsingh (1834) pp. 96–97
- Brown & Ishida (1979) pp. 280–282; Varley (1980), pp. 151–164; Titsingh (1834) pp. 97–102
- Brown & Ishida (1979) pp. 282–283; Varley (1980), p. 164; Titsingh (1834) pp. 103–106
- Brown & Ishida (1979) pp. 283–284; Varley (1980), pp. 164–165; Titsingh (1834) pp. 106–112
- Brown & Ishida (1979) pp. 285–286; Varley (1980), p. 165; Titsingh (1834) pp. 112–115
- Brown & Ishida (1979) pp. 286–288; Varley (1980), pp. 166–170; Titsingh (1834) pp. 115–121
- Brown & Ishida (1979) pp. 288–289; Varley (1980), pp. 170–171; Titsingh (1834) pp. 121–124
- Brown & Ishida (1979) p. 289; Varley (1980), pp. 171–175; Titsingh (1834) pp. 124–125
- Brown & Ishida (1979) pp. 289–290; Varley (1980), pp. 175–179; Titsingh (1834) pp. 125–129
- Brown & Ishida (1979) pp. 290–293; Varley (1980), pp. 179–181; Titsingh (1834) pp. 129–134
- Brown & Ishida (1979) pp. 294–295; Varley (1980), pp. 181–183; Titsingh (1834) pp. 134–138
- Brown & Ishida (1979) pp. 295–298; Varley (1980), pp. 183–190; Titsingh (1834) pp. 139–142
- Brown & Ishida (1979) p. 298; Varley (1980), pp. 190–191; Titsingh (1834) pp. 142–143
- Brown & Ishida (1979) pp. 299–300; Varley (1980), pp. 191–192; Titsingh (1834) pp. 144–148
- Brown & Ishida (1979) pp. 300–302; Varley (1980), p. 192; Titsingh (1834) pp. 148–149
- Brown & Ishida (1979) pp. 302–307; Varley (1980), pp. 192–195; Titsingh (1834) pp. 150–154
- Brown & Ishida (1979) p. 307; Varley (1980), p. 195; Titsingh (1834) pp. 154–155
- Brown & Ishida (1979) pp. 307–310; Varley (1980), pp. 195–196; Titsingh (1834) pp. 156–160
- Brown & Ishida (1979) pp. 310–311; Varley (1980), p. 197; Titsingh (1834) pp. 160–162
- Brown & Ishida (1979) pp. 311–314; Varley (1980), pp. 197–198; Titsingh (1834) pp. 162–166
- Brown & Ishida (1979) pp. 314–315; Varley (1980), pp. 198–199; Titsingh (1834) pp. 166–168
- Brown & Ishida (1979) pp. 315–317; Varley (1980), pp. 199–202; Titsingh (1834) pp. 169–171
- Brown & Ishida (1979) pp. 317–320; Varley (1980), p. 202; Titsingh (1834) pp. 172–178
- Brown & Ishida (1979) pp. 320–322; Varley (1980), pp. 203–204; Titsingh (1834) pp. 178–181
- Brown & Ishida (1979) pp. 322–324; Varley (1980), pp. 204–205; Titsingh (1834) pp. 181–185
- Brown & Ishida (1979) pp. 324–326; Varley (1980), p. 205; Titsingh (1834) pp. 186–188
- Brown & Ishida (1979) pp. 326–327; Varley (1980), pp. 205–208; Titsingh (1834) pp. 188–190188–190.
- Brown & Ishida (1979) pp. 327–329; Varley (1980), pp. 208–212; Titsingh (1834) pp. 191–194
- Brown & Ishida (1979) pp. 329–330; Varley (1980), p. 212; Titsingh (1834) pp. 194–195
- Brown & Ishida (1979) pp. 333–334; Varley (1980), pp. 214–215; Titsingh (1834) pp. 20–207
- Brown & Ishida (1979) pp. 334–339; Varley (1980), pp. 215–220; Titsingh (1834) pp. 207–221
- Brown & Ishida (1979) pp. 339–341; Varley (1980), p. 220; Titsingh (1834) pp. 221–230
- Brown & Ishida (1979) pp. 341–343; Varley (1980), pp. 221–223; Titsingh (1834) pp. 230–238
- Brown & Ishida (1979) pp. 343–344; Varley (1980), pp. 223–226; Titsingh (1834) pp. 236–238
- Brown & Ishida (1979) pp. 344–349; Varley (1980), pp. 226–227; Titsingh (1834) pp. 238–241
- Varley (1980), p. 227; Titsingh (1834) pp. 242–245
- Varley (1980), pp. 228–231; Titsingh (1834) pp. 245–247
- Varley (1980), pp. 231–232; Titsingh (1834) pp. 248–253
- Varley (1980), pp. 232–233; Titsingh (1834) pp. 253–261
- Varley (1980), pp. 233–237; Titsingh (1834) pp. 262–269
- Varley (1980), pp. 237–238; Titsingh (1834) pp. 269–274
- Varley (1980), pp. 238–239; Titsingh (1834) pp. 274–275
- Varley (1980), p. 239; Titsingh (1834) pp. 275–278
- Varley (1980), pp. 239–241; Titsingh (1834) pp. 278–281
- Varley (1980), pp. 241–269; Titsingh (1834) pp. 281–286, 290–294
- Titsingh (1834) pp. 327–331
- Titsingh (1834) pp. 331–351
- Titsingh (1834) pp. 352–364
- Titsingh (1834) pp. 364–372
- Titsingh (1834) pp. 372–382
- Titsingh (1834) pp. 382–402
- Titsingh (1834) pp. 402–409
- Titsingh (1834) pp. 410–411
- Titsingh (1834) pp. 411–412
- Titsingh (1834) pp. 412–413
- Titsingh (1834) p. 413
- Titsingh (1834) pp. 414–415
- Titsingh (1834) pp. 415–416
- Titsingh (1834) pp. 416–417
- Titsingh (1834) pp. 417–418
- Titsingh (1834) pp. 418–419
- Titsingh (1834) p. 419
- Titsingh (1834) pp. 419–420
- Titsingh (1834) pp. 420–421
- Titsingh (1834) p. 421
- The National Diet Library (NDL) website explains that "Japan organized its first calendar in the 12th year of Suiko (604)", which was a pre-nengō time frame; Nussbaum (2005) "Jikkan Jūnishi" p. 420.
- NengoCalc (655) 斉明 Saimei
- NengoCalc (622) 天智 Tenji
- NengoCalc (672) 弘文 Kōbun
- NengoCalc (673) 弘文 Tenmu
- NengoCalc (687) 持統 Jitō
- NengoCalc (697) 文武 Monmu
- Bramsen, William. (1880). Japanese Chronological Tables: Showing the Date, According to the Julian or Gregorian Calendar, of the First Day of Each Japanese Month, from Tai-kwa 1st year to Mei-ji 6th year (645 AD to 1873 AD): with an Introductory Essay on Japanese Chronology and Calendars. Tokyo: Seishi Bunsha. OCLC 35728014.CS1 maint: ref=harv (link)
- Brown, Delmer M.; Ishida, Ichirō, eds. (1979). The Future and the Past: a translation and study of the Gukanshô, an interpretative history of Japan written in 1219. Berkeley, CA: University of California Press. ISBN 978-0-520-03460-0. OCLC 251325323.CS1 maint: ref=harv (link)
- Daijirin, 2nd edition.
- Daijisen, 1st edition.
- Kōjien, 5th edition.
- Murray, David (1894). The Story of Japan. New York: G.P. Putnam's Sons. OCLC 1016340.CS1 maint: ref=harv (link)
- NengoCalc. Online conversion of Japanese dates into their Western equivalents; calculation is based on tables from Tsuchihashi (1952) and Zöllner (2003).
- Nussbaum, Louis-Frédéric (2005). Japan encyclopedia. Translated by Käthe Roth. Cambridge: Harvard University Press. ISBN 978-0-674-01753-5. OCLC 58053128.CS1 maint: ref=harv (link)
- Ponsonby-Fane, Richard. (1959). The Imperial House of Japan. Kyoto: Ponsonby Memorial Society. OCLC 194887
- Titsingh, Isaac (1834). Nipon o daï itsi ran: ou Annales des empereurs du Japon (in French). Translated by Titsingh, Isaac. Paris: Royal Asiatic Society, Oriental Translation Fund of Great Britain and Ireland. OCLC 5850691.CS1 maint: ref=harv (link) Nihon Ōdai Ichiran
- Tsuchihashi, Paul Yashita (1952). Japanese chronological tables from 601 to 1872 (邦曆西曆對照表: 自推古九年至明治五年, Hōreki seireki taishōhyō: Suiko kyūnen yori Meiji gonen ni itaru) (in Japanese). Tokyo: Sophia University. OCLC 001291275.CS1 maint: ref=harv (link)
- Varley, H. Paul (1980). Jinnō Shōtōki: A Chronicle of Gods and Sovereigns. New York: Columbia University Press. ISBN 978-0-231-04940-5. OCLC 59145842.CS1 maint: ref=harv (link)
- Zöllner, Reinhard (2003). Japanische Zeitrechnung: ein Handbuch. Munich: Iudicium Verlag. ISBN 9783891297834. OCLC 249297777.CS1 maint: ref=harv (link)
- 二中歴1 第一～第四（尊経閣善本影印集成） ISBN 4-8406-2314-7.
- 二中歴2 第五～第十（尊経閣善本影印集成） ISBN 4-8406-2315-5.
- 二中歴3 第十一～第十三（尊経閣善本影印集成） ISBN 4-8406-2316-3.
- 所功, (1977). 日本の年号 揺れ動く＜元号＞問題の原点. 雄山閣.
- 井上清, (1989). 元号制批判 やめよう元号を. 明石書店. ISBN 4-7503-0236-8.