- "In ancient times, people believed that light was a gift from an unseen land by the name of Kingdom Hearts. But Kingdom Hearts was safeguard by its counterpart, the χ-blade. Warriors vied for that precious light, thus beginning the "Keyblade War". The violent clash shattered the χ-blade into twenty pieces—seven of light and thirteen of darkness. And only the real Kingdom Hearts was swallowed by the darkness, never to surface again."
- —Master Xehanort
Both Yen Sid and Xehanort revealed that when the World was whole and full of light people desired the power of Kingdom Hearts, many creating the first Keyblades in order to obtain the means to control Kingdom Hearts: the χ-blade. However, many sides clashed over who would get the χ-blade, causing a massive war that consumed everything in darkness as the ancient weapon was shattered into twenty peices, seven of pure light and thirteen of pure darkness, and the "true" Kingdom Hearts disappeared into the darkness.
However, the light within the hearts of children kept the darkness at bay yet separated the worlds from each other. The remnants of the battlefield on which the Keyblade War took place became the Keyblade Graveyard, littered with 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, ages later, Xehanort came upon the story of the Keyblade War and resolved to recreate the χ-blade by causing a second Keyblade War.