Dark ages are often quite durable.
The Latin West likes to forget that the Roman Empire didn’t fall with Rome, but staggered on like a golem for 1100 years under their fascistic new regime. The emperors were worshipped as semidivine figures anointed by God; you can still see the haloes on their ikons in Orthodox churches.
Under the brutish rulers’ absolute authority, the Christian empire long outlasted the old civic life of res-publica it burnt to the ground. The police state torched Saracen ships with Greek fire as eagerly as they did heretics and “pagan” academies.
No one dared to stop it. No one either in or against the novo ordem did, at least. The people had forgotten how, forgotten how to think beyond the hegemonic order of the Abrahamic world-state. Yet somehow some canny archives survived in monastery back rooms, mouldering on wormy shelves, copied as samizdat by the rare contrarian or cosmopolitan scribe.
Our archives must likewise be built to last for generations, to ensure learning endures such epochs. It goes without saying so far we are very unprepared.