“Zhengyue” Was Not Originally the First Month of the Year

Last revised: 2026-10-18

Chujia Kuang (邝楚嘉)

Independent Researcher, Jieyang, Guangdong, China

Corresponding author: Chujia Kuang, Independent Researcher, Jieyang, Guangdong, China. E-mail: chirca@163.com

Abstract

Zhengyue (正月) is ordinarily taken to mean the first month of the year. The two were not always the same thing. This note sets out the san zheng (三正), the three reckonings of the year’s beginning that the sources attribute to the Xia, Shang and Zhou, and lists the month each took as its head. The Qin is added to that list: its year opened in the tenth month, and the Qin did not call that month zhengyue — it renamed zhengyue as duanyue (端月) instead, while the four seasons continued to run by the Xia reckoning. The restoration is traced to the Taichu li of 104 BCE, which fixed the head of the year at the first month; that arrangement has held for two thousand years, with four interruptions after it (Wang Mang, the Wei emperor Ming, and twice under the Tang, including Wu Zetian’s manufacture of an auspicious date in 698). The note then separates three things the sources keep distinct — the head of the year, the name zhengyue, and the pairing of seasons with months — citing Sima Zhen’s commentary on the Shiji, and records Wang Li’s doubt as to whether the san zheng can be credited at all. It closes with Shen Kuo’s unadopted proposal for a purely solar calendar of months divided by solar terms. The note is descriptive; it contains no predictive claims.

Keywords: zhengyue; san zheng; head of the year; Taichu calendar; Zhuanxu calendar; Qin calendar; Shen Kuo

1. The three zheng: which month heads the year

Start with the claim itself.

The two characters zhengyue (正月) did not originally mean the first month.

They meant the month in which the head of the year falls — the first month of the year. And which month that was has been changed many times in the course of more than two thousand years.

Travel back to the Qin and celebrate the New Year there, and that month is the tenth.

The ancients fixed the months by the seven stars of the Dipper. Whichever direction the handle points to establishes (建, jian) that month; the months 寅, 卯 and 辰 are named in this way.

Which month stood at the head of the year differed from dynasty to dynasty:

Dynasty	Dipper handle	Head of the year, by today’s reckoning
Xia	jian 寅	the first month
Shang	jian 丑	the twelfth month
Zhou	jian 子	the eleventh month
Qin	jian 亥	the tenth month

The ancients called this body of rules the san zheng (三正), the three beginnings.

Hu Sanxing, annotating the Zizhi tongjian, states it most clearly:

古有三正：子为天正，周用之，以十一月为岁首; 丑为地正，殷用之，以十二月为岁首; 寅为人正，夏用之，以十三月（即一月）为岁首。
(There were three beginnings. 子 is the celestial beginning, used by the Zhou, which took the eleventh month as the head of the year; 丑 is the terrestrial beginning, used by the Yin [Shang], which took the twelfth month; 寅 is the human beginning, used by the Xia, which took the thirteenth month — that is, the first — as the head of the year.)

The Shiji, “Treatise on the Calendar”, has a line as well:

夏正以正月，殷正以十二月，周正以十一月。
(The Xia took the first month as their corrected beginning, the Yin the twelfth, the Zhou the eleventh.)

The preceding note, on the double-hour 子, mentioned that the Zhou took the eleventh month as the head of the year and midnight as the beginning of the day. This is the same matter.

Mind the positions of Shang and Zhou: Shang is the twelfth month, Zhou the eleventh. The two are easily reversed, and not a few accounts do reverse them. The text of the Shiji is the standard.

2. The Qin year began in the tenth month

After the First Emperor united the six states, the calendar in use was the Zhuanxu li, and the head of the year was fixed at the month jian 亥 — the tenth month by the Xia reckoning.

So the New Year in Qin was kept in autumn.

One detail must be kept clear: the Qin did not call the tenth month zhengyue. They renamed zhengyue as duanyue (端月), and the pairing of seasons with months continued as before by the Xia reckoning — spring still being the first, second and third months.

A further point. Zhengyue is read zheng yue today. The most widely repeated account is that this avoids the personal name of the First Emperor, 正 and 政 being homophones — the same motive as the change to duanyue. Huang Sheng of the Qing had already rejected that account in his Zigu: the character 正 had a level-tone reading of its own, and was not produced by taboo.

This will matter again shortly.

The early Han went on using the Qin calendar, and did so for more than a hundred years. When Liu Bang took the throne, the New Year ceremony was held in the tenth month. The Shiji, “Biographies of Liu Jing and Shusun Tong”, records that in the seventh year of Emperor Gao of Han the Chang Le Palace was completed and the marquises and ministers all came to court in the tenth month — the palace had just been finished, and the lords and ministers hurried to present their congratulations in the tenth month.

3. Emperor Wu of Han put it back

Under Emperor Wu, in the first year of Taichu, 104 BCE, the matter was settled.

The Taichu li was promulgated that year; it restored the Xia reckoning, jian 寅, and took the first month once more as the head of the year. The work was led by Sima Qian, then Grand Astrologer. Among the more than twenty who compiled the calendar, the calendar officer Deng Ping and Luo Xiahong of Ba commandery contributed most, and the master of methods Tang Du was in charge of the celestial section.

The preceding note, on the twelve double-hours, mentioned the Taichu li as the point at which the twelve took their final form. This is another thing done by the same calendar: it fixed the head of the year as well.

The Taichu li had a longer consequence still. It was the first calendar to incorporate the twenty-four solar terms, and it laid down the rule that a month without a qi is the intercalary month. The skeleton of today’s lunisolar calendar was built then.

From the first year of Taichu, “head of the year” and “zhengyue” became one thing — the first month of the year was zhengyue.

It sounds flat, but it has governed the two thousand years since.

4. After it was changed back, it changed four more times

A change of dynasty required “correcting the first month and changing the colours of dress”, as a sign that the mandate had passed. So after the Taichu li the head of the year moved again several times:

Years	Who	Changed to
8—23 CE	Wang Mang	the Shang reckoning (twelfth month)
237—239	Emperor Ming of Wei, Cao Rui	the Shang reckoning
689—700	Wu Zetian	the Zhou reckoning (eleventh month)
761—762	Emperor Suzong of Tang	the Zhou reckoning

The middle episode is the one with a story.

Wu Zetian was preparing to take the throne. In the eleventh month of the first year of Yongchang (689) she issued an edict adopting the Zhou reckoning, fixing the eleventh month as the first month of the new year, renaming the twelfth month 腊月 and renaming the old first month 一月.

The consequence: the first year of Yongchang had only eleven months, and 325 days.

In that year the people of China lived through a year of 325 days.

Her motive for moving the head of the year was political, not calendrical.

Nine years later (698) she did it again. The calendar officers reckoned that the following year should carry an intercalary twelfth month; what she wanted was for the first day of the first month to fall on “jiazi, new moon at dawn, winter solstice” — the term, the month order and the day-count all beginning on the same day, the hardest of auspices in the eyes of the ancients. She found a pretext, ordered the intercalary month moved elsewhere, forced the day into existence, and at once changed the era name to Shengli.

Modern scholars, back-calculating with the Linde li and astronomical tools, find that the winter solstice of that year fell on the day 壬戌, not 甲子.

The auspice was manufactured.

In the tenth month of the first year of Jiushi (700) she changed it back. The Zizhi tongjian records the reversal bluntly: “On the day jia-yin, an edict restored the first month as the eleventh month, and 一月 as zhengyue.”

5. The head of the year, zhengyue and the seasons are three separate matters

Return to that detail from the Qin.

The Qin took the tenth month as the head of the year, yet did not call the tenth month zhengyue, and ran the four seasons by the Xia reckoning. What does this show?

That for the ancients “head of the year”, “zhengyue” and “which months pair with which seasons” could be three separate matters.

This is not the later reader dividing what the ancients had joined. Sima Zhen of the Tang, annotating the Shiji, writes plainly under the line about the court gathering in the tenth month:

汉以十月为正，故行朝岁之礼，史家追书十月也……案：诸书并云十月为岁首，不言以十月为正月。
(The Han took the tenth month as their corrected beginning, and so performed the ceremony of the new-year court; the historian writes the tenth month after the fact. … Note: the various books all say that the tenth month was the head of the year; none says that the tenth month was zhengyue.)

The tenth month was the head of the year; zhengyue was still zhengyue. More than a thousand years ago, readers of history already kept the two apart.

Keeping them apart, though, is still a matter of how to read old books. One step further down the question changes: does the doctrine of the san zheng itself hold up?

The linguist Wang Li took it as grounds for doubt. If the three dynasties really used three different calendars, why did the Qin not simply rename the tenth month zhengyue?

The reminder is useful when reading old texts.

The Chunqiu, under the first year of Duke Cheng, records that “in the second month there was no ice”. Du Yu’s note on the line runs to six characters: the second month of the Zhou, the twelfth month of today. The second month of the Zhou calendar is the twelfth of the Xia, precisely the coldest time; that the river did not freeze was why the scribe set it down gravely. Read it as the second month of the Xia and the line makes no sense — by then the ice should long since have broken.

Without knowing the difference in the head of the year, one takes the ancients to have made a mistake.

6. A clever proposal that was not adopted

Shen Kuo, in the Northern Song, thought of another way out.

In the Mengxi bitan, “Supplementary Notes”, he proposed setting the moon aside and laying out the months purely by solar terms:

直以立春之日为孟春之一日，惊蛰为仲春之一日，大尽三十一日，小尽三十日，岁岁齐尽，永无闰余。
(Take the day of lichun as the first day of the first spring month, the day of jingzhe as the first day of the second; let the long months run to thirty-one days and the short to thirty; every year then comes out even, and there is never a surplus to intercalate.)

Lichun would be the first day of the first month, jingzhe the first day of the second; the long months would have thirty-one days and the short months thirty, and no intercalary month would ever be needed.

This is a purely solar calendar. It runs almost exactly along the lines of the stem-and-branch calendar — both divide the months by solar terms, and neither needs an intercalary month. As the note on the three calendars said, the stem-and-branch calendar works that way. The difference is that the stem-and-branch calendar never became the everyday calendar of ordinary people, while it has continued in use in charting to this day.

Shen Kuo knew the proposal would draw abuse. He wrote after it:

今此历论，尤当取怪怒攻骂，然异时必有用予之说者。
(This calendrical argument of mine will above all provoke astonishment, anger and attack. Yet another time will certainly find men who use my proposal.)

Abused at the time; sooner or later someone would use it. Read nine hundred years later, the sentence does not sound as though it were addressed to the Song.

Closing

In the course of two thousand years the meaning of the two characters zhengyue has shifted several times. To say “the first day of zhengyue” today points to one thing; to say zhengyue in the Qin points to another month.

What comes next in this series is the clock — the time on a watch is not the double-hour of your birth.

Note on the text

This is a popular exposition, and it makes no claim to original research. The astronomical constants cited are standard values. This English version is issued alongside the Chinese original as the same article in another language. The author’s name is 邝楚嘉, Chujia Kuang; he writes under the pen-name 嘉言一得 (Jiayan Yide).

Declarations

Funding. This research received no external funding.

Competing interests. The author declares no competing interests.

Data availability. No new data were created or analysed in this study.

Language. The original Chinese text is deposited as a companion file to this record (正月本来不是一月).

References

[1] Chunqiu [春秋][M]. Pre-Qin period.

[2] Sima Qian. Shiji [史记][M]. With commentary by Sima Zhen. Western Han.

[3] Sima Guang. Zizhi tongjian [资治通鉴][M]. With commentary by Hu Sanxing. Song dynasty.

[4] Shen Kuo. Mengxi bitan [梦溪笔谈][M]. Song dynasty.

[5] Huang Sheng. Zigu [字诂][M]. Qing dynasty.

Images in this article are illustration only; they are not evidence and not a basis for any statement of fact.

This article is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).
You are free to reprint, redistribute, or build upon it, including for commercial purposes, provided you credit the original author as 「嘉言一得（Chujia Kuang 邝楚嘉）」 and include a link to the original publication.
Copyright in the excavated Qin and Han bamboo-slip photographs and in the transmitted texts quoted here remains with their respective rights holders and is not covered by this licence.
For the full terms of the licence, see: https://creativecommons.org
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Chinese editions: 正月本来不是一月（the original Chinese text of this essay）

Site hubs: Glossary ｜ Calendar Reform ｜ Publications

All data in this article were collected and compiled by Chujia Kuang.

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作者：嘉言一得（邝楚嘉）｜独立研究者，致力于可核验的原始文献与历法数据归档。
Author: Chujia Kuang (邝楚嘉), pen name Jiayan Yide (嘉言一得) — independent researcher devoted to archiving verifiable primary sources and calendar data.
平实记录 · 数据集 · 预印本：GitHub / WordPress / Zenodo（DOI: 10.5281/zenodo.22788686 ／ 10.5281/zenodo.23028692）
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