Strictly speaking I don't think "back country" correctly defines what was in Deliverance.
Back Country is like the High Sierras and generally when you are more than a day's hike from any kind of permanent housing structure . I think of back country as where the biggest danger is wild animals like Grizzly Bears. Therefore the back country is actually where humans are the most civilized with each other. Because they need to be.
What was portrayed in Deliverance was kind of just the opposite. Its a place where people could farm land and hunt. Americans settled there in the 18th century. Because they were able to make a living they didn't have to change.