The folk music of rural Appalachia -- primarily concentrated in western Pennsylvania, West Virginia, western North Carolina, eastern Kentucky, and Tennessee -- provided much of the basis for bluegrass and country music. Centered around stringed instruments -- fiddle, guitar, bass, mandolin, banjo, dulcimer, etc. -- and rudimentary percussion (if any), Appalachian folk largely descended from English and Scots-Irish folk traditions, brought to the region by colonial immigrants seeking territory and farmland to call their own; there were also smaller influences from other European immigrants, African-Americans, and Native Americans. Because of the rugged landscape, transportation and communication were difficult, leaving the region's culture and music to develop in relative isolation over the course of the 1800s. Life in the mountains was often tough and lonely, and music became the most popular means of expression and entertainment. Appalachian folk songs were simple and covered all facets of everyday life, both extraordinary and run-of-the-mill -- work (especially coal mining, logging, and working on the river), love, death, religion (including many traditional hymns), and murder (the famed ballad of "Tom Dooley" originated here). Known as old-timey music or hillbilly music, Appalachian folk began to find popular acceptance during the 1920s thanks in part to its traditional values, which were also fairly well ingrained in the culture at large. The recordings of the Carter Family helped preserve crucial parts of the Appalachian folk repertoire, and helped pave the way for both country music and, especially, bluegrass (birthed in the '40s thanks to the work of Bill Monroe). Evolution of the Appalachian folk tradition was inevitable by this point, since the music's popularity was accompanied by hordes of talent scouts, opening both the region and its performers up to a great deal of outside influence. However, even if Appalachian folk is no longer a thriving tradition (due mainly to ever-increasing outside influence and a population exodus from the still-impoverished area), the music is still the subject of much preservationist fascination, and has become virtually synonymous with American folk tradition.