First introduced as a concept in The Compleat Discworld Atlas, the Great Outdoors fleshes out a hitherto great big void on the old Discworld Mapp running from the Rammerock Mountains and NoThingfjord rimward out to the sea widdershins of Kythia. It covers some two thousand miles of open space, and is described as a patchwork haven of many disparate refugee groups fleeing from trouble or persecution elsewhere on the Disc; possibly a place to bring your tired and huddling masses who are yearning to breathe free, sundry wretched refuse of assorted teeming shores, and those who are generally homeless and tempest-tost. Or who have simply had it up to here with the storied pomp of ancient lands and all the grief it's capable of causing.
The religious, ethnic and linguistic groupings are many and varied, ranging from The Very, Very, Very Plain Omnians of the Slaked Plains to refugees from Borogravia who fled over the border to excape Nugganism and conscription into the endless wars. They settled along the line of the New Kneck River, which apparently does not move much, a point in its favour. Dwarfs and humans from NoThingfjord fled here and set up the nearest thing to a capital city, New Nothing, to escape interminable and compulsory Sagas. Presumably someone lived there before these trespassers, too--perhaps this, rather than Howondaland, is where One-Man-Bucket's family actually came from?
There is no government as known elsewhere and no common currency: a complex trading and barter system takes its place. The people are described as linked by a common deep paranoia, mistrust of authority and slowness to accept strangers. Hmm.
Idiosyncratic religious groups. Refugees fleeing persecution. Economic migrants. A hardy self-reliant people with a paranoid streak and a distrust of excessive government. Hmm. What was it that was said many years ago about no part of the Discworld resembling any part of North America, by express command... somewhere in here there must be a settlement called Power Cable...