The planet of Ceolfre is known as a "cautionary tale". A world inhabited by a series of technologically advanced cultures, the Ceolfreans (Or whatever they called themselves in their near endless diversity), allowed their technical achievements outpace their social ones. As a result when many of the nations achieved the capability to fight a nuclear conflict it was only inevitable that the missiles flew and vast swathes of the planet were turned into irradiated wastelands. Nuclear winter set in, millions starved while others fled underground. In the end a mere fraction of the society survived. Now hundreds of years later vast scavenger cities roam the wastelands, searching for raw materials to exploit. Inhabited by the descendants of the Ceofreans who had fled underground, they are territorial and fierce.
The "roaming cities" are self sufficient, growing food within while also sending out hunting parties for the creatures who survived the nuclear winters. They are also well armed so anyone approaching a roaming city may be taking their lives into their hands.
Ceolfreans are rugged individualists, they are taught from an early age to shoot a wide variety of weapons and fix/juryrig just about every piece of machinery that makes up their environment. They are also taught a wide variety of survival skills; environments that would kill a normal person is a walk in the park for the inhabitants of Ceolfre.