The World-That-Was, also called the World Before Time and the Broken World, and once known informally as the "Warhammer World" or just the "mortal world," is the name given to an ancient inhabited planet that preexisted the Mortal Realms and was destroyed by the unified power of Chaos long millennia ago in another age of the Cosmos Arcane.
Many of the Mortal Realms' divine beings, Chosen and even many of the common people of all species can trace their existence back to when they were inhabitants of the World-That-Was at some point in its lost history.
All have been reincarnated into new physical forms or have been slightly altered in essence from their original incarnations.
The metallic core of the World-That-Was, known as "Mallus" and the "Broken World," was hurled through the Cosmos Arcane by the force of the world's destruction, dragging the ascended human god Sigmar, once a native of this world, with it. Mallus was eventually caught up and placed in the firmament of Azyr, the Realm of Heavens, by the Godbeast and Great Drake Dracothion.
Sigmar forged a necklace of sigmarite from the core of the World-That-Was for Dracothion in gratitude, and now Mallus hangs above Sigmaron, the great city of the God-King, in the Realm of Azyr. There it is orbited by the Sigmarabulum, a vast ring of forges and other structures created by Dracothion, Grungni, the duardin god of smiths and Tyrion, the aelven god of light and war.[1a]
The World-That-Was' white moon, Mannslieb, also now hangs above the spires of Sigmaron as well.