
The genre emerged in the early 1980s as musicians began fusing the double bass drumming and complex guitar stylings of the new wave of British heavy metal (NWOBHM) with the speed and aggression of hardcore punk and the technicality of progressive music. Philosophically, thrash metal developed as a backlash against both the conservatism of the Reagan era and the much more moderate, pop-influenced, and widely accessible heavy metal subgenre of glam metal which also developed concurrently in the 1980s.