The Great Ice Dark is the Mute name given for the historical period immediately following on from the War of a Thousand Suns. According to legend, at this time the world was shrouded in darkness and no living thing seemed to stir on the face of the earth.
According to Amtrak Federation records, this was actually the period of nuclear winter following the atomic exchanges of the war. Lethal amounts of radiation had been released through the air, and vast quantities of dust and debris had been hurled into the atmosphere by the thousands of nuclear explosions that wracked the world. Vast areas of urban development and forests were also left ablaze by the war, and these fires spread and burned out of control for months on end. The world was shrouded in a thick blanket of smog and cloud that lasted for years and reduced global temperatures severely, resulting in freezing winters.
The duration of the 'Great Ice Dark' is unclear, but is believed to have been at least several decades. The forebears of the Trackers survived in their immense underground bunkers beneath Texas, but most of the human race who had survived the war died during these decades of freezing cold that followed. The tiny number of ordinary people that survived these challenges went on to become the forebears of the Mutes and the Iron Masters.