With its origins in southwest Louisiana house dances in the 1920s, uptempo, syncopated zydeco blends blues, rhythm and blues, and Cajun, black, and some Native American traditions - as well as, as of the 1950s, rock and roll.  It makes heavy use of the accordion and the vest frottoir, an adapted washboard worn on the chest, and is also more heavily influenced by Southern black music tradition, as opposed to the more white-influenced (and least in my observation) Cajun music tradition, with its roots in the folk music of French-speaking Acadiana in Nova Scotia, whence many Louisiana settlers came. 

Terry Ballard