3000 Years Ago - The Dark Purge
3000 Years Ago the boarders of the Realm In-Between was sieged by radical Light Keyblade Masters who wanted to overthrow the Darkness and destroy anyone whom followed it, the main order at the Land of Departure abandoned the radicals to do what they wanted while neither backing nor stopping the purge, then Emperor Allias Dark led an Army of Dark Keyblade Wielders and other Warriors out to stop them. Needless to say that it was a grueling task, it was much like dealing with a fierce Resistance force, it took years to kill them all off with some becoming mass murderers however by the time of their defeat many were dead.
1000 Years Ago - The 1st Great Keyblade War
Deep Dive City:
Alley to Between
The Alley to Between hides a portal to Betwixt and Between, the alley way connects to the main route that leads to the Castle That Never Was.
Fragment Crossing is a long series of winding streets that lead to Memory's Skyscraper. It is full of neon signs attached to vacant buildings as well as a power plant which seems to power some or all of the city. Many Shadow Heartless are here.
Memory's Skyscraper is a tall building in the World That Never Was. Located near the Castle That Never Was, the building kept watch over the residents of the Dark. On its front, it has a massive television screen that seems to flash images of memories of those nearby. It is also used as a Tower Castle by Blaid Dark when speaking to his people and listening to their requests.
Brink of Despair
The Brink of Despair seems to have been made by The Castle That Never Was which hovers above it, the crator it hovers over is actually all that remains of the Castle that was there before it over 1000 years ago before the X-Blade was used on a drastic attack on the Capital before it was finally destroyed, the pit is actually a maximum security prison that only certain portals can exit by going through a Bewixt and Between.
Betwixt and Between
There are a number of these around the Dark Empire and it is revealed that they are magical checkpoints for those whom use the Dark Corridors, those who do not have the right authorisation to enter the following area is sealed out, they are then attacked by numbers of Heartless and Nobodies whom are led by either a Humanoid Nobody or an Unversed.
The Castle That Never Was
The Heart of the World that Never Was and the Dark Empire. See: Castle That Never Was - Capital.
Memory's Contortion is an area that included Memory's Skyscraper in its design, it is designated a man-made battle zone that is summoned to fight enemies.