We have a couple of questions asking where something comes from and is essentially history-related.
The ones here probably aren't as useful for modern language use.
Japanese/Chinese numbers usage timeline
Origin of the circle in ぬ, ね, and る
These are seen on a regular basis on the Internet so they serve a purpose.
Where does なう on Twitter come from?
Do we draw a line anywhere for history questions or are we not really concerned as long as they asking for the origin of some Japanese word or phrase?