For you lore hounds that missed the end of an age, I'll direct you here:
http://gamerescape.com/2013/08/21/th...e-white-raven/

As a fair warning, depending on the person, this will take anywhere between 30-90 minutes to read. It's a detailed chronological run-down of the series of events that led up to the 7th Umbral Era.

Now there may be clues of this in ARR, so it may have spoilers for those who want to feel as if they're playing through the game with the same sense of confusion about the "Warriors of Light" as the NPCs. However, if you want to know just what happened to our poor Eorzea, it's worth a read.

Enjoy, and only 29 hours to go for EA!