The World-That-Was, also called the World Before Time, and once known informally as the Warhammer World or just "the 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 and Chosen can trace their existence back to when they were mortals at some point in the lost history of the World That Was.
Its metallic core, known as "Mallus," was hurled through the cosmos by the force of its destruction, dragging the god Sigmar, once a native of this world, with it. Mallus was eventually caught up and placed in the firmament by the 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, where it is orbited by the Sigmarabulum, a vast ring of forges and other structures created by Dracothion, Grungni and Tyrion.[1a]
The World That Was' white moon, Mannslieb, also now hangs above the spires of Sigmaron as well.