I'm going to be running a campaign in the forgotten realms soon. I don't have time to read all the books on it. Could you guys summarize some of its history for me?

Thanks!

Hahahahahahaha, that's funny.

It's a pretty large body of lore and not easily summarized. There's the whole macro level events like the Sundering, but I don't find that stuff particularly relevant.

Read the Sword Coast Adventurer's Guide. I also often use the forgotten realms wiki. Find Youtube videos on its history.  

If you don't have time for this then why are you DMing? Maybe you can improvise. 

Yeah, I agree. This is like asking someone to summarise the Monsters Manual. Or the history of the earth.

I guess if I was going to be at all helpful, just focus on what you need for your current campaign and research more as you go....

Spine of the world is up the top and cold and nasty.

The sword (west) coast has Neverwinter and Waterdeep, 2 of the biggest cities in the realms.

Thay is in the mid east and is pretty horrible. Slavery and all that. Thayan Red Wizards are a bad bunch.

The middle has a fair few swamps and stuff, but the continent is massive.

https://forgottenrealms.wikia.com/wiki/Main_Page - The wiki helps if you are looking for info on a particular place/person/thing.