Heavy Metal music was developed in the early 1970's.
 The 1970 releases by Black Sabbath (Black Sabbath, which is generally accepted as the first heavy metal album, and Paranoid) and Deep Purple (Deep Purple in Rock) were crucial in this regard
 During the mid-1970s, Judas Priest helped spur the genre's evolution by discarding much of its blues influence, while Motrhead introduced a punk rock sensibility and an increasing emphasis on speed

