Manntis formed in Riverside County, California in 2000 and gained wider exposure in 2004 as contestants on MTV's Battle for Ozzfest, a platform that led directly to a worldwide deal with Century Media Records. The band's debut album Sleep in Your Grave was released in June 2005, featuring a melodic metalcore sound that positioned them alongside the mid-2000s Southern California heavy scene. Despite plans for a follow-up album, no further full-length materialized, leaving Sleep in Your Grave as their sole major label statement.

San Francisco's Mordred are one of the most distinctive acts to emerge from the late-1980s Bay Area thrash scene, fusing tight thrash riffing with funk grooves and hip-hop sensibilities in a way that sounded unlike anything else at the time. Reactivated and recording since 2020, they continue to occupy a genre-crossing space that defies easy categorization.

Sacramento metalcore act Murdered by Horses arrived in 2023 with the kind of absurdist menace in their name that belies a genuine commitment to the genre's heavy mechanics. California's capital city has long punched above its weight in aggressive music, and this young band adds to that tradition.