NATIVE AZERBAIJANIAN THEORISTS OFTEN INTRODUCE THE FOUNDATION of mughams through scales. For example, in Principles of Azerbaijanian Folk Music, Hajibeyov discussed mugham-modes by describing the tonal and intervallic scale construction. Zokhrabov begins the analysis of the dastgahs Rast and Chahargah by presenting the scales of the two mughams. The scale can be divided into smaller units. Navvab, for example, believed that mugham is based on four softas (four tones forming a tetrachord) (Safarova, 1987: 125). Hormoz Farhat, writing about Persian art music, suggested that "some modes may be adequately expressed within the range of a tetrachord or a pentachord" (Farhat, 1990: 18). Hajibeyov saw the scale of Bayati Shiraz as a "combination of tetrachords" connected by an "intermediate tone" (Hajibeyov, 1985: 22).