Was it this? It seems to fit the perfect timeframe for the mysterious era which has always left historians baffled.
Mankind has always wondered how Byzantine Rome mysteriously vanished and this sea of the unknown descended on mankind. The written record just largely skipped over 200 years of what apparently was a huge collapse of society worldwide. The Chinese call this period "The Tail of the Black Dragon" according to their records. It was recorded as a miserable epoch of famine and darkness.
This is where all the disputes arise as people puzzle over this basic question ... why were people forced to fill in the gaps of this period with mythology and monsters? How could the inhabitants of Europe have gone from 8 story monolithic temples with columns 30 meters in diameter to living in stone huts and barely being able to eke out a subsistence diet? This is the era when the legends of Camelot arose and a huge epistemology was created of fantastic conjecture. Why did the survivors of this era even lack a solid oral tradition for two centuries? Luckily we have fragments but organized society seems to have taken a holiday for well over a hundred years during this period.
Then again, maybe instead of a violent catastrophic event that destroyed civilization, it may have just been an ancestor of George Soros doing what they do best. George knows how to collaborate with anybody, including the Nationalist Socialist Party of Germany.