It's not exactly a science. When it comes to artistic movements (literature, arts, music, performance) artists don't have to exclusively belong to one particular movement or group. Musicians in particular can belong to multiple movements in multiple areas, but even in literature movements are more defined by how the work's style is influenced than its locale. To an extent, subgroups exist (think of the Lost Generation as an example) to delineate parts of larger movements, but they're certainly not perfectly aligned. On top of that, it's also important to remember that artistic endeavor of all movements share mediums for this exact reason - how a work of art is influenced counts infinitely more for how its classified than either the artist or the work's subject / setting.