My family knew it well.
/not born right-wise
The Scotch-Irish arrived here largely in the 17th and 18th centuries, many of whom were indentured servants, who then worked off their term of indenture and headed west into the then-frontier backcountry on the eastern side of the Appalachians, then into the Appalachians and beyond after the US became a nation. Being largely Presbyterian they were not particularly liked by the establishment Church of England types so they had motivation to leave as well as something of a predisposition for hilly country. So west they went.
My family knew it well.
/not born right-wise