My sense is the Smurfs were probably inspired by Brigadoon, a famous Broadway musical (Lerner & Loewe) that was adapted into a very famous film starring Gene Kelly and Cyd Charisse.
The story involves two American tourists who stumble upon Brigadoon, a mysterious Scottish village that appears for only one day every 100 years.
Brigadoon (wiki)
The name Brigadoon derives from the real Brig o' Doon, a bridge near Alloway, Scotland, and a feature of Robert Burns' folkloric poem Tam o' Shanter.
It's possible the Brigadoon story derives from folktale, but I'm not finding any reliable online sources. I did an excerpt attributed (without specific citation) to a book Lost Lands, Forgotten Realms: Sunken Continents, Vanished Cities, and the Kingdoms That History Misplaced which reads: “the spell that was cast over Brigadoon was put in place to protect it from advancing English Redcoats during the Jacobite Rebellion.”