Persian Dastgah
The modal system at the heart of Persian art music. A dastgah is one of seven principal modal frameworks (supplemented by five derivative 膩v膩z), each defined by a characteristic scale, melodic motifs (gusheh), opening material (daramad) and conventions of ascent, emphasis and cadence. Performers improvise within the dastgah by traversing its gushehs in a sanctioned order drawn from the radif, the memorised canonical repertoire codified in the nineteenth century, so that each rendition functions simultaneously as modal exposition, composition and improvisation.