That said, the game wiki is full of many famous characters / influential events. I believe anything in the game wiki is considered fair game IC knowledge, and it'll probably fill in some of the gaps you're looking for.
I believe that most players find out right on the www.sindome.org homepage near the top that the game is set "85 years in the future", before they even log in. Others ask in Game-Help before writing a history.
It could be made more prominent, I suppose.
Otherwise, world events up to 2090 is plenty to develop a character history from. Immigrants aren't supposed to know all the world history unless they're ICly educated before immigrating. And immigrants aren't supposed to know Withmore history *at all*, no matter how long their *player* has been on Sindome. Still, you do have Lore and the Globe for helping your character get clied fast. The Globe is even available outside the MOO, under the Newsfeed part of the website.