The History of the Garden Empire
The Before Times Sequence
Garden Age advanced thawing of the peat bogs (intentionally or as a byproduct of activities) → Cryogenically frozen creatures, including elves and goblins emerge from thawing zones as if still in battle (disoriented, aggressive, displaced, desperate) → Garden Age People of Brinemarch faced an existential threat (annual waves of thawed monsters. ) → Garden Age infrastructure and culture declines as participants migrate away, and engineers transform the landscape for survival (i.e. it was not mysterious disappearance, but a planned exodus)
The Garden Empire setting:
Old Garden Age = 200 years ago Oral tradition from grandparents' who's grandparents knew survivors. Ruins match the stories.
Antiquity Garden Age = 1000 years ago Oral tradition keeps legends, but key Garden Age knowledge fragmented. Ruins have decayed, land has shifted.