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    Bluegrass music is a form of American roots music. It was named by Bill Monroe who named his band The Blue Grass Boys. The Bluegrass boys played a Mountain Music style that Bill learned in Asheville North Carolina from bands like Wade Mainer's and other popular acts on radio station WWNC. the 1939–1996 band of Kentucky mandolin player and songwriter  Bill Monroe, who is considered "the father of bluegrass".

    It was further developed by musicians who played with him, including 5-string banjo player Earl Scruggs and guitarist Lester Flatt. It was then evolved by other musicians who admired the high-energy instrumental and vocal music Monroe's group created, and who carried it on into new bands, some of which created subgenres of bluegrass.

     Bluegrass is influenced by the music of Appalachia and other styles, including gospel and jazz. Appalachian music itself has mixed roots in Irish,  Scottish and English traditional music, and was also later influenced by the music of African-Americans through incorporation of jazz and blues elements.

     Some bluegrass musicians in this group are Jimmy Martin, Doc Watson, J. D. Crowe, Doyle Lawson, Sam Bush, Béla Fleck, John Hartford, Jerry Douglas, Norman Blake, Frank Wakefield, Bill Keith, Del McCoury, Tony Rice, and the pioneering female duo Hazel Dickens & Alice Gerrard. As they refined their craft, the New Grass Revival, Seldom Scene, Kentucky Colonels, and The Dillards  developed progressive bluegrass.

      Bluegrass fiddler Vassar Clements, progressive mandolin player David Grisman,  Grateful Dead frontman Jerry Garcia (on banjo), and Peter Rowan on lead vocals played in the band called Old & In the Way. Garcia, Chris Hillman, Dickey Betts of The Allman Brothers Band and others in the 1960s and 1970s helped introduce rock music listeners to progressive and traditional bluegrass. Bush, Grisman, and Clements developed strong jazz elements in most of their playing—Clements liked to refer to his music as "hillbilly jazz"—but each owes much to traditional bluegrass.

^{Source:  https://en.wikipedia.org/wiki/Bluegrass_music}