Dastgah

Dastgāh (Persian: دستگاه‎) is a musical modal system in traditional Persian art music. Persian art music consists of twelve principal musical modal systems or dastgāhs; in spite of 50 or more extant dastgāhs, theorists generally refer to a set of twelve principal ones. A dastgāh is a melody type on the basis of which a performer produces extemporised pieces.