The Aftermath.
And here we have the other great dark period of our modern history.
We know considerably more about the Aftermath than we do the Interstitial. The Aftermath has been called by some a “chaotic” period, but in reality it was, if anything, too ordered. It is marked by a radical increase in authoritarianism and what, in an early age, would have been called “fascism,” but what we today refer to as corporatism.*
It would take the new, post-human cultures rising in the Solar Colonies to bring Earth to its senses nearly a century later.
*A term coined, oddly enough, by the man who “invented” fascism in the early 20th century (old reckoning). Read up on Benito Mussolini if you are interested.