I can think of a lot of examples where ex-patriot communities have kept something alive which had died out 'back home', but that isn't really what you're looking for, Jerry. A different example is the triple-harp which (I think?) originated in Italy but died out there - yet it's still played in Wales. (perhaps elsewhere?) But that was just attrition of something which had been quite wide spread at one time.

Can't think of any examples where a completely separate community took to a 'foreign' practice so much that they became a major force in conservation ...

sian