As the principal architects of Southern rock, the Allman Brothers Band forged this new musical offshoot from elements of blues, jazz, soul, R&B and rock and roll. Along with the Grateful Dead and Cream, they help advance rock as a medium for improvisation. Their kind of jamming required a level of technical virtuosity and musical literacy that was relatively new to rock & roll, which had theretofore largely been a song-oriented medium. The original guitarists in the Allman Brothers Band—Duane Allman and Dickey Betts—broke that barrier with soaring, extended solos. Combined with organist Gregg Allman's gruff, soulful vocals and Hammond B3 organ, plus the forceful, syncopated drive of a rhythm section that included two drummers, the Allman Brothers Band were a blues-rocking powerhouse from their beginnings in 1969.