Editing Chinese calendar (section)

===Week===
{{For|more information on the adoption of the seven-day week|Names of the days of the week#East Asian tradition}}
{{For|more information on the ten-day week|Decan}}

As early as the Bronze Age [[Xia dynasty]], days were grouped into nine- or ten-day weeks known as {{zh|labels=no|c=旬||p=xún|out=p}}.<ref>{{cite book | author = {{zh|labels=no|c=海上}} | title = Zhongguo ren de sui shi wen hua | script-title = zh:中國人的歲時文化 | trans-title = Timekeeping of the Chinese culture | publisher = {{zh|labels=no|c=岳麓書社}} | year = 2005 | pages = 195 | isbn = 978-7-80665-620-4 | language = zh | url = https://archive.org/details/zhongguorendesui0000hais/page/195 }}</ref> Months consisted of three {{tlit|zh|pinyin|xún}}. The first 10 days were the early {{tlit|zh|pinyin|xún}} ({{zh|labels=no|c={{linktext|上旬}}}}), the middle 10 the mid {{tlit|zh|pinyin|xún}} ({{zh|labels=no|c={{linktext|中旬}}}}), and the last nine (or 10) days were the late {{tlit|zh|pinyin|xún}} ({{zh|labels=no|c={{linktext|下旬}}}}). Japan [[Japanese calendar#Division of the Month|adopted this pattern]], with 10-day-weeks known as {{nihongo|''jun''|旬}}. In Korea, they were known as ''sun'' ({{langx|ko|label=none|순}},{{langx|ko|label=none|旬}}).

The structure of {{tlit|zh|pinyin|xún}} led to [[Public holidays in China|public holidays]] every five or ten days. Officials of the [[Han dynasty]] were legally required to rest every five days (twice a {{tlit|zh|pinyin|xún}}, or 5–6 times a month). The name of these breaks became {{zh|labels=no|t={{linktext|澣}} |s={{linktext|浣}} |l=wash |p=huàn |out=p}}.

Grouping days into sets of ten is still used today in referring to specific natural events. "Three Fu" ({{linktext|三伏|lang=zh}}), a 29–30-day period which is the hottest of the year, reflects its three-{{tlit|zh|pinyin|xún}} length.<ref name="3 fu">{{cite web |url=http://www.hko.gov.hk/prtver/html/docs/education/edu01met/wxobs/folklore/ele_hs_c.shtml |author={{zh|labels=no|c=陳浩新}} |script-title=zh:「冷在三九，熱在三伏」 |trans-title=Cold is in the Three Nines, heat is in the Three Fu |website=Educational Resources – Hong Kong Observatory |language=zh  |access-date=15 May 2018 |archive-url=https://web.archive.org/web/20180615134946/http://www.hko.gov.hk/prtver/html/docs/education/edu01met/wxobs/folklore/ele_hs_c.shtml |archive-date=15 June 2018 |url-status=dead }}</ref> After the winter solstice, nine sets of nine days were counted to calculate the end of winter.<ref>{{Cite web |script-title=zh:数九从哪一天开始到哪一天结束 数九寒冬中的数九从什么时候开始 |url=https://wannianli.tianqi.com/news/281436.html |access-date=2023-05-02 |website=万年历 |archive-date=30 April 2023 |archive-url=https://web.archive.org/web/20230430033214/https://wannianli.tianqi.com/news/281436.html |url-status=live }}</ref>

The seven-day week was adopted from the Hellenistic system by the 4th century CE{{Citation needed|date=September 2023}}, although its method of transmission into China is unclear. It was again transmitted to China in the 8th century by [[Manichaeism|Manichaeans]] via [[Kangju]] (a Central Asian kingdom near [[Samarkand]]),<ref>{{cite web |url=http://www.cjvlang.com/Dow/dowjpn.html |website=CJVLang |title=Days of the week in Japanese |access-date=15 May 2018 |archive-date=24 December 2017 |archive-url=https://web.archive.org/web/20171224044408/http://www.cjvlang.com/Dow/dowjpn.html |url-status=live }}</ref>{{efn|The 4th-century date, according to the ''[[Cihai]]'' encyclopedia,{{year needed|date=April 2015}} is due to a reference to Fan Ning ({{zh|labels=no|t={{linktext|範寧}}|s={{linktext|范宁}}}}), an astrologer of the [[Jin dynasty (265–420)|Jin dynasty]].{{Full citation needed|date=October 2018}}}}{{efn|The renewed adoption from Manichaeans by the 8th century ([[Tang dynasty]]) is documented by the writings of the Chinese Buddhist monk [[Yijing (monk)|Yi Jing]] and the Ceylonese Buddhist monk [[Amoghavajra|Bu Kong]].{{Full citation needed|date=October 2018}}}} and is the most-used system in modern China.