Calamity

The calamity is the terrible effect that happened to cause the lost empire to fall.

Fallen Empire, Romanesque 200 years in the past, was magic the cause? Archeotechnology, tried to marry magic and technology, arcane atom bomb went off destroyed the empire itself. Roadside picnic style magic chaos zone in the centre of the continent, separating groups and disrupting travel. Ground zero is potentially beside us on the continent, the whole game takes place in a corner of that empire. Great reason to avoid external influence.