Disaster / Destruction
A Cataclysmic event of unknown scale and detail that forced the first residents into the Vault.
The exact details of the Cataclysm has been a topic of discussion and scrutiny by many scholars and historians, for historical evidence and details seem to be in contradiction of one another. The exact timing of the Cataclysm has been identified to have been as early as 5000 B.F, and as close as 338 B.F. However, what is clear is that an unknown event forced the original residents into the Vault and by unknown means, put them all into a state of slumber and stasis. The Vault itself is of mysterious origin, no one knows who built them, and for what purposes. But one thing the founding fathers knew was that the Vaults saved the very last flicker of civilisation.