I believe the generally accepted view is that the Wall is located along the path of the M4 (projected from coast to coast). So the Iron Throne (seat of the King of the Seven Kingdoms) is located near Arundel, the Warden of the North resides in Windsor. So everything north of Bracknell/Reading/Slough/Newbury etc is Wildling territory, over-run with the walking dead, white walkers and white dragons.
HTH,
PDR