The book is set in a post-apocalyptic world, ravaged by a "Sixty Minute War", which caused massive geological upheaval. To escape the earthquakes, volcanoes, and other instabilities, a Nomad leader called Nikola Quercus (known as god Nicholas Quirke by the time of the book) installed huge engines and wheels on London, and enabled it to dismantle (or eat) other cities for resources. The technology rapidly spread, and evolved into what is known as "Municipal Darwinism". Although the planet has since become stable, Municipal Darwinism has spread to most of the world except for Asia and parts of Africa. Much technological and scientific knowledge was lost during the war. Because scientific progress has almost completely halted, "Old Tech" is highly prized and recovered by scavengers and archaeologists. Europe, some of Asia, North Africa, Antarctica, and the Arctic are dominated by Traction Cities, whereas North America was so ravaged by the war that it is often identified as "the dead continent", and the rest of the world is the stronghold of the Anti-Traction League, which seeks to keep cities from moving and thus stop the intense consumption of the planet's remaining resources.