Hypothetically, if governments wordwide just suddenly became authoritarian and deleted all records of history, you and some survivors escape to a remote area outside of government control, they all can’t remember much from history (either didn’t pay attwntion in class, or suffers memory loss from the governemtn attacks) and so you are designated as this community’s official historian. How much can you remember? What’s gonna be the official narrative of your little rebel community?
The government doesn’t control all the information. I’ll still have my offline copy of Wikipedia, on my phone, that contains a lot of the world’s history. Apart from that I just remember some mythology, some stuff about the Sumerians, Egyptians, Greeks, Romans, Incas, British, Americans, and Indians, plus a reasonable understanding of WW2 and the holocaust, plus various historical events that have happened in my lifetime.
This hypothetical is assuming you are in an active warzone (think like 1984’s world) and have no time to find your stuff, or you just accidentally drop it while running away from government troops.
You just had to run until you find a safe place (like a secret underground bunker or something) and have nothing on you beside your memories.
While I understand it doesn’t quite fit the scenario, it does strike me as a good way to preserve “lost information” in a similar situation. Pair that with a solar charger (or even improvise something like a pedal charger), and you’re pretty set for a lot of basic information people would struggle to reconstruct.
Some ebook readers have a microsd card slot, so you could fit an offline copy of Wikipedia on a device with half a year of battery life (in airplane mode)
Congratulations, you’ve just written a quarter of the plot of the Book of Eli with Denzel Washington