Claim: Black Sabbath are often referred to as trailblazers of a type of rock music that advanced in the late 1960s and early 1970s.
Evidence: Black Sabbath are often cited as pioneers of heavy metal music.
Heavy metal -LRB- or simply metal -RRB- is a genre of rock music that developed in the late 1960s and early 1970s , largely in the United Kingdom and the United States.