Folk music bluegrass and country all grew out of the traditional mountain region.?

That's right. Folk music, bluegrass, and country are all genres that originated in the traditional music of the Appalachian Mountains in the United States. These genres share many common roots and influences, including traditional English, Scottish, and Irish folk songs, as well as African-American spirituals and blues music. Bluegrass is generally considered to be the most traditional of these genres, while folk music and country have both seen considerable evolution and diversification over the years.