I believe Western Europe. In the circles I run in "nihlism" is code for Western Europe.
...and in those circles, "nihilism" also identifies "modernism," against which ChesterBelloc fought valiantly...
John Paul II has made this call before, specifically mentioning (dare I mention it?) France as one of the chief wellsprings of a satanic spirit of "too cool for school". He specifically mentioned a couple of cities as being the most particular fonts of this rot -- Lyons, France, I think was one of them.
He was very specific in naming these places. I don't recall whether it was a book or an encyclical, I think the latter; but reflecting on that old memory the other day while watching some of the solemnities during the pope's vigil, the penny suddenly dropped that it may not be a complete coincidence that France is suddenly overrun with millions of violent, bloodyminded Arabs bent on persecuting Jews (for now). Now, whose fault is that?
The very people John Paul II pointed his crozier at.