Bay Area thrash metal (also known as Bay Area thrash) referred to a steady following of heavy metal bands in the 1980s who formed and gained international status in the San Francisco Bay Area in California. Along with Central Florida, the scene was widely regarded as a starting point of American thrash metal, crossover thrash and death metal. History Exodus and Metallica The earliest documented roots of the Bay Area thrash scene date back to the formation of Exodus in 1979. By the time the group recorded their full-length album four years later, five different guitarists or bassists had already passed through the line-up, with some going on to join or form bands that were equally relevant to the area's burgeoning metal scene. In November 1982, Exodus opened a show at San Francisco's Old Waldorf venue for Metallica, a then-relatively unknown (and unsigned) band from Southern California who were recently discovered by Brian Slagel and had appeared on the first volume of his Metal Massacre compilation. Exodus (who were also unsigned at this time) had distributed an untitled demo the same year with a line-up that included guitarist Kirk Hammett. Although Metallica had initially formed in Los Angeles, it was not until their February 1983 relocation to the East Bay area that Cliff Burton formerly from TRAUMA joined as bassist, sealing the band's first, formative line-up. The group (which then consisted of Burton, James Hetfield, Lars Ulrich, and Dave Mustaine) had moved into a Carlson Blvd. house in El Cerrito, near Albany Hill, which had been rented by Mark Whitaker, then-manager of Exodus. After Mustaine was removed from the line-up that same year, then-Exodus guitarist Hammett would replace him following Whitaker's recommendation; in turn, Mustaine would move back to Los Angeles to form Megadeth. Metallica's signing to Megaforce Records, the release of their first album and the songwriting process and rehearsals for Ride the Lightning and Master of Puppets had all taken place while the group resided at Whitaker's El Cerrito home. Networking between local bands Burton and Hammett's friendship with other local acts, notably Oakland's Exodus and Testament, and later, San Francisco's Death Angel—among others—strongly vitalized the scene, leading to intensive touring and tape trading that would cross borders and seas, and eventually graduate to record signings. El Sobrante's Possessed would bring a turning point to the genre with 1985's Seven Churches, regarded as the first album to cross