As we reached the '90s, rock had started to get a whole lot heavier. After the hair metal scene slowly started to embarrass itself towards 1989, the influx of grunge and alternative rock bands pretty much stomped out any chances of metal reaching the mainstream. On the other hand, there was a way to keep things sludgy without throwing on spandex.
Coming out of the California desert, Kyuss was one of the first bands to bring about what became known as stoner rock. Looking to get a different sound for the time, guitarist Josh Homme started to tune down his guitars to previously unheard of levels, which resulted in some of the meatiest grooves ever to be put to vinyl. The sound may have been indebted to someone like Black Sabbath, but the way in which these guys turned their riffs inside out on albums like Blues for the Red Sun made them fit right in alongside the heavier grunge acts like the Melvins.
Not long afterwards, other bands like Monster Magnet and Sleep started to throw their hat into the ring, with slow dirge-like songs that feel great when "chemically enhanced." Even though all of the pieces were there from the beginnings of metal, it wasn't until Kyuss came along that we got the stoner rock bible.