Complex sentence: Other Bay Area based bands like Exodus, Metallica, Death Angel were also starting out during that era-and were playing the same local venues and establishing the Bay Area thrash metal scene-which in a few years would became very popular worldwide.
Split into simpler sentences: Other Bay Area-based bands like Exodus, Metallica, and Death Angel were also starting out during that era. These bands were playing the same local venues and establishing the Bay Area thrash metal scene--which in a few years would become very popular worldwide.