Overview
The Maelstrom is a dangerous warp rift and storm region near the dense stellar masses of the galactic core, roughly between Terra and Ultramar, that has long offered shelter to renegades and raiders.
Its hazards are navigational, military, and political, because unstable space makes authority difficult to enforce.
Unlike a normal frontier, the Maelstrom resists being tidied into a border.
During the Thirteenth Black Crusade the Maelstrom swelled and became part of the Great Rift, its storms merging with the galaxy-spanning wound rather than standing apart from it — the faint M42 tendril reaching down to it on the map marks that joining.
M41 and M42 status
Warp rift and raider haven in Ultima.
Swollen into the Great Rift during the 13th Black Crusade; a storm-zone now joined to the galaxy's wound.
Timeline
Ultima route warnings mark the Maelstrom as a persistent no-go hazard.
Raider activity rises from storm-shielded approaches.
Imperial commanders reinforce nearby systems after repeated attacks.
The Maelstrom expands into the Great Rift, no longer a separate hazard but a southern extension of the same wound.
Cartographic positions and several administrative details are intentionally approximate where published Warhammer sources conflict or provide no canonical coordinate system.