The River Reik is the greatest river of the Old World and the artery through which the lifeblood of the Empire flows. Rising in the Grey Mountains and the World's Edge, its countless tributaries — the Talabec, the Stir, the Aver, and a hundred lesser streams — drain nearly the whole of the Empire before the Reik broadens into its vast estuary and empties into the Sea of Claws at the port of Marienburg.
Every great Imperial city stands upon its waters. Altdorf rules from the confluence of Reik and Talabec; Nuln casts its cannon where the Aver joins the flow; and an endless traffic of riverboats, barges, and merchant craft moves grain, iron, wine, and soldiers along its length. River-wardens and the boatmen of the Reik keep the channels open, for whoever commands the river commands the trade and the movement of armies alike.
The Reik is more than a trade road — it is a border, a battlefield, and a symbol. Its bridges have decided the fate of provinces, its fords have run red in a dozen wars, and its waters bind the feuding lands of the Empire into a single body politic more surely than any Emperor's decree. To sail the Reik from the mountains to the sea is to travel the whole span of the Empire of Man, and to see why the nation, for all its quarrels, holds together at all.