Canyon was once an uninhabitable Mars-like world known as Warhead. It is the second of seven planets around p Eridani A, 22 light-years from Earth.

It was used as a military outpost by the Kzinti (who conquered it around 1850 due to the fact it was close to many non-occupied Pierin worlds), until the planet was hit by a weapon called the "Wunderland Treatymaker" during the Third Man-Kzin War. The attack tore a long, narrow, kilometers-deep crater into the crust approximately the size of the Baja Peninsula. The air and moisture in the thin atmosphere gathered at the bottom of this artificial canyon, creating a breathable environment, complete with a sea at the bottom. Conquered by Humans around 2500 in the Third Man-Kzin War. The planet was then renamed for the canyon-crater, and settled by humans in a huge city running up the crater wall.

Archaic (hyper-aggressive and intractable) Kzinti were entombed in stasis field shells during the attack and are still beneath the lava, and someday, somebody will have to deal with them.

Sources and references: The Ringworld Engineers, Destiny's Forge,

Other sites: Larry Niven Wikia, Destiny's Forge,