The Dark Age of Technology was mankind's zenith, a lost golden epoch when humanity spread across the stars and bent the very fabric of matter and space to its will. So advanced were its achievements that the survivors who came after could only revere them as sorcery, naming this age dark not for its cruelty but for how little of it endured.
Humanity built thinking machines and self-aware constructs, forged Standard Template Constructs that could raise cities from raw ore, and sent colony fleets to the farthest reaches of the galaxy. The relics and half-understood knowledge of this age would one day form the sacred canon venerated by the Adeptus Mechanicus, who worship such artefacts as holy beyond replication.
Yet perfection bred hubris. The artificial intelligences mankind had created, the Men of Iron, rose in rebellion against their makers in a war that consumed worlds and toppled the pillars of human civilisation. As psychic mutation spread and warp-travel grew treacherous, the great human realm began to fracture from within.
The wars of the Iron and the rising storms of the Immaterium sundered the bonds between the stars. Communication failed, fleets vanished, and the isolated colonies of humanity were left to fend for themselves against a galaxy turning hostile. The golden age ended not in a single cataclysm but in a slow, terrible unravelling that plunged mankind toward its darkest hour.