Great Keyblade War

The Great Keyblade War was an event that lasted more than five-thousand years and ended a hundred years before the events of Kingdom Hearts: Generations.

About
In the "age of fairy tales", the World was whole and full of light, which was believed to come from Kingdom Hearts, which was protected by its counterpart, the χ-blade. Over time, people came to desire the power of Kingdom Hearts, introducing darkness into the World.

In order to take control of Kingdom Hearts, many people forged Keyblades in the image of the χ-blade, and they clashed together in a far-reaching conflict that embroiled the entire World. In the end, darkness covered the World, the χ-blade was shattered into twenty pieces, seven of pure light and thirteen of pure darkness, and the "true" Kingdom Hearts disappeared into the darkness.

However, the World was restored by the light within the hearts of children, but as many individual worlds separated from each other. The remnants of the battlefield on which the Great Keyblade War took place became the Keyblade Graveyard, a scarred wasteland filled with the Keyblades of fallen warriors. The remaining Keyblade wielders resolved to protect the World from further destruction, becoming guardians of the World order.

The story of the Keyblade War was passed into legend, and the Keyblade was depicted both as a bringer of chaos and destruction and as a weapon to save the World.

However, during the war there were a mysterious group who watched over the Great Keyblade War only to be great for their wisdom and hearts pure than any else, these people were known as the Twenty-Six Keys founded by the first Keyblader of Light, Grandmaster Lei Hong.