 During the 2000s, many more metalcore bands became known.Bullet for My Valentine, Killswitch Engage, Atreyu, Shadows Fall, and As I Lay Dying all had some popularity during the 2000s.In the mid-1980s, northern West Coast bands such as Melvins, Flipper and Green River developed a sludgy, "aggressive sound that melded the slower tempos of heavy metal with the intensity of hardcore," creating an alternative rock subgenre known as grunge.