System Of A Down rose to prominence in the age of nu-metal, but the group’s socially conscious lyrics have far more in common with the ’90s punk underground and political firebrands such as Rage Against the Machine. The California band’s songs condemn war, violence and oppression, with 2005’s “Holy Mountains” specifically raising awareness of the Armenian Genocide, an early-20th-century event that affected family members of frontman Serj Tankian. Guitarist Daron Malakian and Tankian initially started playing music together in the early ’90s. On the group’s self-titled 1998 debut, piledriving metal riffs and Tankian’s gruff vocals made them mainstream metal darlings; the band opened for Slayer and Metallica and landed a slot on Ozzfest. However, beginning with 2001’s Toxicity, System Of A Down leaped into an entirely distinct musical realm, thanks to Malakian’s unorthodox approach to composition. Unique time signatures, dizzying rhythmic passages and Tankian’s motormouthed vocal delivery collided with inventive guitar work based around stinging riffs (“B.Y.O.B.”), evocative soundscapes (“Aerials”) and prog-calibre complexity (“Hypnotize”). In the hands of other bands, this combination might have sounded convoluted or chaotic, but System Of A Down’s methodical technique and intellectual bent led to greatness up until 2005’s Hypnotize, after which the band took an extended hiatus from recording to focus on live dates.