We need to realize that cataclysmic events now are known about world wide with in minutes or even seconds of the event happening. In terms of "Skyrim technology" for spreading information a cataclysmic event somewhere else in the world that did not have any effect on Skyrim, might not ever be known for certain and written down as history. It would be word of mouth from someone who had survived the event and then travelled to Skyrim, spreading the story in the process. However the key word there is "story" because the people in Skyrim would have no solid proof, just the word of some travelers.

But we hear people talk about things like The American Revolutionary war, The French Revolution, American Slavery etc. It is likely that, 140 years from now, people will still talk about The Holocaust. None of these things are constant conversations in most people's everday lives, but they certainly come up in discussion, even outside of history classes, in regards to politics, society etc. because they had lasting effects.

I don't think anyone will have forgotten that Two Hundred years ago in Tameriel. . . All Hell Broke Loose. . . Literally. Especially since some of the Elves would have been alive at the time of Oblivion, and since it is likely that, even when the gates closed, some of THe Daedra already in Nirn probably got left behind. And who knows what these immortal stragglers may have gotten up to.

Ummmm. . . In America, The American Revolution is celebrated with Fireworks every Fourth Of July. Every year in December people break out Nativity Scenes and sing about an event they believed to have happened about two thousand years ago. I have a feeling that an event like Oblivion would not be soon forgotten by anyone. We might not talk about Ceaser, or Attilla the Hun, or The Pharoahs of Egypt everyday. . . but we all have at least a tacit knowledge of their having existed, and they do come up form time to time.