Sun studios before that Chess records Acoustic musicians from the Deep South migrated north before and after WW 2 They amplified their instruments and augmented their performances with bass guitar and drums so they could be heard by raucous audiences. Delta style blues was played at House parties and West side Chicago clubs. This new sound appealed to black working class relocated people because it reminded them of home. They could blow off steam, dance and shake to amplified blues As commercial pop music evolved, rock and rollers emulated blues bands hence guitar, bass and drums became a model to new rock and roll innovators