[nextlevelwizard]

Or maybe, just maybe, it could have been about some actual forgotten country where only name of a city or something survived?

Obviously you can use whatever title you want and be as poetic as you like, but at least in my mind I was going to a very different place than "mathematician".

As for your examples, they don't really fit, since we have way more context about them. If you are going to see a movie with a title "No country for old men", you can be pretty sure that the title wont be literal (unless it's an comedy movie, in which case it might be). As for the quote, most people get that "past" is past and not some place and certainly they are not going to start looking for "yesterday" like you suggest, that's just stupid of you to even suggest. Anyone who is aware that "yesterday" is part of "past" already knows what you are talking about. However most people do not know who or even what Grothendieck, to me it doesn't even seem like a name of a person, but that's just me.

EDIT: You can downvote me all you want, but unless you can come up with coherent response, please think twice why you are downvoting.