"Peter Klaus" is a German folk tale. The story was written as Peter Klaus the Goatherd by Johann Karl Christoph Nachtigal.
Peter Klaus Wikipedia
The story follows a German goatherd from a fictional village named Sittendorf. While looking for escaped goats, Peter Klaus is led to where others are playing games in the woods. After tasting their wine, he falls asleep and wakes up twenty years later.
The story was part of the inspiration for American writer Washington Irving's 1819 short story "Rip Van Winkle".