> The Chinese had apparently adopted the seven-day week from the Hellenistic system by the 4th century, although by which route is not entirely clear. It was again transmitted to China in the 8th century by Manichaeans, via the country of Kang (a Central Asian polity near Samarkand).[20] The 4th-century date, according to the Cihai encyclopedia,[year needed] is due to a reference to Fan Ning (范寧), an astrologer of the Jin Dynasty. The renewed adoption from Manichaeans in the 8th century (Tang Dynasty) is documented with the writings of the Chinese Buddhist monk Yijing and the Ceylonese Buddhist monk Bu Kong.

> The Chinese transliteration of the planetary system was soon brought to Japan by the Japanese monk Kobo Daishi; surviving diaries of the Japanese statesman Fujiwara no Michinaga show the seven-day system in use in Heian Period Japan as early as 1007. In Japan, the seven-day system was kept in use (for astrological purposes) until its promotion to a full-fledged (Western-style) calendrical basis during the Meiji era. In China, with the founding of the Republic of China in 1911, Monday through Saturday in China are now named after the luminaries implicitly with the numbers.

The naming scheme also holds for French, except for Saturday (samedi [0]) and Sunday(dimanche [1]), which originates from "Day of Shabbat" and "Day of the Lord". But according to wikipedia [0], samedi replaced the "Day of Saturn".

[0] https://fr.wikipedia.org/wiki/Samedi

[1] https://fr.wikipedia.org/wiki/Dimanche

"Sábado" is Spanish for Shabat as is Sabato in Italian

(I'm sure other romance languages are similar, even Portuguese, that has Sábado and Domingo, but the rest of the days are numbered from 2nd to 6th, oddly enough)

All of them coming directly from Latin

What? They use the same seven-day week today.

They name the days "one", "two", "three", etc, which was actually an innovation by Christian missionaries in China, not the Chinese themselves. The seventh day is named "day" rather than being numbered, so that the full name is 礼拜天 "the day of worship", anchoring the week firmly to the Christian week.

(The same effort to rename the days of the week along more Christian lines was also made in Europe, but it didn't take there.)

> the rough translations into anglo-saxon/norse gods applies (tyr/tiw, thor, freija)

I was kind of amused to see "anglo-saxon/norse" followed by "tyr/tiw"; Tyr is the Norse form and Tiw is the English form.

(The goddess honored by Friday was Frig in English, and Thor is of course Thunor -- his name is nothing but the ordinary word "thunder".)

But I don't think even most Japanese people are aware of this today; the only common use of 曜 is its use in the name of every weekday, so people think of 火曜日 as being segmented 火-曜日, the weekday ("曜日", etymologically spurious) of fire (火).

I don't know the modern Japanese word for Mars, but in Chinese it's 火星, not 火曜.

The fire light being Mars.

> I don't know the modern Japanese word for Mars, but in Chinese it's 火星, not 火曜.

火星 is the same. I don't know about Chinese, but in Japanese 曜 can be a general word for the sun, the moon, and stars (七曜).

Maybe for the second one you meant "names of the planets"?

China is a relative latecomer here and typically lags these types of ancient civilizational innovations, with the oldest being Mesopotamia and Egypt. In China, the seven day week was adopted in the late 4th Century A.D. in the Jin dynasty roughly 3000 years after it was adopted in Mesopotamia.

There are two theories as to the origin of the seven day week, one that it started in ancient Babylon and another that it started in ancient Egypt.

The concept of a "week" is directly tied to the concept of a sabbath (a special holy day to mark the end of the week). This, in turn is related to Babylonian numerical systems -- they had a base 6 system corresponding to 6 days of work followed by the religious day, and hence the origin of our seven day week. Interestingly, unlike in judaism where the seventh day is considered one in which work was forbidden as God rested on that week, in Babylonian tradition, the seventh day was considered unlucky for work and thus work was to be avoided. It is a fine line separating these different notions of a Sabbath and thus of the week.

Another speculated origin for the week was via lunar observations -- e.g. a quarter phase of the moon corresponding to a half-moon either waxing or waning with a lunar month being roughly 29.5 days, so 1/4 of that would be 7.4 days. But there are different ways to divide this -- e.g. a sequence of 7 day units followed by a sequence of special days tacked at the end or some other combination. You actually see these types of divisions in some ancient Babylonian calendars. But with a base 6 system, there are some nice divisions, e.g. 6 days of work followed by the holy day = 1 week

4 weeks followed by a holy day at the end = 1 month

the residual .5 day, can accumulate so that after 12 months, 12*.5 = 6. 6 special days to be added at the end of 12 months.

In the ancient past, you had different regions practicing their own calendar system and one of the first innovations of the first (known) empire in Mesopotamia was the standardization of weeks and months as different cities were brought into the Sumerian empire. Sargon I of Akkad is said to have standardized the week by ensuring that the different cities he conquered were synced up and observed the same set of extra holy days in what is the first (known) empire

https://www.tandfonline.com/doi/pdf/10.1179/0308018827898012...

However there is some linguistic evidence that the Sumerians merely borrowed the concept of a week from the Akkadian civilization, so the earlier Akkadian civilization is believed to have held the concept of a week first.

Once you have the notion of a week, it is not hard to name it after the sun, moon, and 5 celestial planets, as these were the primary astronomical phenomena. You can see these names in ancient languages here: https://www.hermetic.ch/cal_stud/hlwc/why_seven.htm

I think this needs a citation. I've never seen any mention of 7-day weeks in historical Chinese texts. Systems of 7-day weeks might be known by Chinese by this time due to cultural and religious exchanges with the West, but claims that it was "adopted" is news to me. My impression is that the current 7 day week system adopted in China is a very recent phenomenon, i.e. presumably not earlier than the 19th century, and mostly due to the work of Christian missionaries. (... I could be wrong though, I haven't read that much post-Jin texts...)