When/how were standardized week days adopted universally? (i.e. who decided the week was 7 days long, and got everyone to know that sunday was sunday and monday was monday)

by greywood

As a follow up, besides small tribes and such are there any countries or regions that do not use a 7 day week?

Searocksandtrees

hi! there's lots of room for more input to cover more cultures but FYI, there's a section in the FAQ on this:

Weeks, weekdays, and weekends