The Cathayan Bastion, called the Great Bastion, is the colossal wall that guards the northern frontier of Grand Cathay against the endless hordes that spill down from the Chaos Wastes and the Eastern Steppes. Stretching for hundreds of miles across the empire's northern marches, it is the mightiest fortification in the world — a work of stone, sorcery, and gunpowder raised at the command of the Celestial Dragon Emperor to hold back the tide of the north.
The Bastion is far more than a wall. Along its length rise watchtowers, fortresses, and beacon-stations, garrisoned by the disciplined jade-armoured legions of Cathay and their war-machines, and woven through with protective magic and the ancient ley-lines the Cathayans call the Dragon Paths. When one beacon is lit, the warning races along the whole length of the wall in moments, and armies muster to meet the threat.
Every generation the Bastion is tested. When the winds of Chaos blow strong, the tribes of the steppe and the beasts of the Wastes throw themselves against it in their tens of thousands, and the Storm of Chaos batters its towers. Yet through age after age it has held, for behind it stands the accumulated might of the oldest and most populous of human realms. To the folk of Cathay the Great Bastion is the shield of civilisation itself — the line beyond which lies only the howling dark, and before which the ordered world endures.