I love KH, but as has been pointed out before, it adds a lot of lore to it. The video linked in the article seemed to know more about the Keyblade War than I thought was known. The only thing I know about it at this point is that it was a war between Keyblade wielders and was sort of a Light-vs-Dark-but-no-one-wins kind of thing.
So, this leads me to, what do we officially know about the Keyblade War? What was it about, who started it, the whole shebang.
The only things known about the Keyblade war is everything revealed in Birth By Sleep and the upcoming (for americans/EU) Dream Drop Distance.
The basic surmise of the war is exactly explained in the lore vid above explained in BBS by Master Xehanort. Many Keyblade masters desired the power for Kingdom Hearts and found out the only way to open Kingdom Hearts was to create the χ-Blade by fusing hearts of pure darkness and pure light.
This war was, obviously, very devastating to the world and eventually, all the Keyblade Masters were wiped out, leaving just this war-torn battlefield and remnants of the master's blades.
This war is also alluded to near the end of the original Kingdom Hearts, during the sequence where you're watching Kairi's memory of her grandmother's tale of a great war that caused darkness in the land, solved only by the Princesses of Heart, restoring light to the world.
