A couple of things.
First, I would have a broad, concise overview. And since it's history, maybe a "villains and saviors of the land" and what they are doing now. Just everyman knowledge and not even all of that considering the level of detail you are talking about. A few recognizable names and a couple of items max.
After the players create up their characters, give them each a 1 page max "some things YOU know". Try not to have much overlap, but rather have that things will fit together with other player's pages so they can riff off each other if it comes up. Do NOT assume that any of ti will be read or remembered - this is so that characters can get some spotlight time showing off their unique knowledge, and by owning it make it more likely they remember. Also, tailor the length of these to how interested the players will be. Even if a character is in the perfect position to now somethign, if the player isn't the type to pull it out give them just a little bit so it's hard to forget.
Introduce them slowly. I know you want their first adventure to be saving the princess - don't make those sessions too reliant on the info. Introduce a bit, build on it, and repeat it occasionally so it doesn't get forgotten.
If you really want intrigue and think your players are up for investing some time via email, write up some short blurbs for some folks of moderate power who aren't adventurer types but are prominent. Head of the local bread bakers and tavern owners guild, second in command of the beggars or maybe chairman of a church council. Have each player pick one. Each week between session feed them a little bit of "behind the scenes" politics that isn't the party's current focus, asking them how their "mover and shaker" would respond. Use this to engage the players, feed them more info in a way they'll care about because it's immediately useful, and get a chance to repeat names of important folks often and get them to make their own impressions - much better to retain then telling them.