Mazo were the pionners of Doom Metal in Peru, or like they simple called it, Heavy Rock. Formed in 1987 with Coco Cortés (Oxido, Tortura, Grael) on bass and vocals, Ñaka Almeyda (Jerusalem) on drums and Billy Astete on guitars. They were influenced by Black Sabbath, Pentagram, Celtic Frost and their debut show was in the No Helden in 1988 with Almas Inmortales, Kranium and Sepulcro with a full packet show.

Later that year Christian “Chamán” replaced Billy on guitars. His first released was a split tape with Sentencia called “En Honor a la Demencia” in 1990 (Rereleased in 2020 by Xaria Music). The next recording was a tape called “El Valle del Miramiento Interior” in 1992, a promo tape for a Spain trip of Coco's (getting a review on Heavy Rock Mag). Andres Parodi replaced Christian in 1993, and they recorded the “Nivel de Vida” demo in 1994 and “Del Azar a la Creacion” album in 1995 (released in 2012), “Mentenegra” (2008) and “Peregrinaje” from 2013 to 2016 (unreleased). The band split up in 1996 after the relocation of Coco to the USA, but the band reformed in 2003.