of the compositions are extant, the names have survived for some, and they suggest a wide variety in the topics he musically engaged with. Ethnomusicologist Hormoz Farhat has tentatively sorted them into different groupings: epic forms based on historical events, kin-i Iraj (), kin-i siavash (), and Taxt-i Ardashir (); songs connected to the Sasanian royal court, Bagh-i shirin (), Bagh-i Shahryar (), and haft Ganj (); and "compositions of a descriptive nature", roshan charagh (). According to both scholars Ibn al-Faqih and the 13th-century geographer Yaqut al-Hamawi, Barbad wrote Bag-e nakjiran () for workers who had recently finished the gardens of Qasr-e Shirin. A single poem by Barbad survives, though in a quoted state from the Kitab al-lahw wa al-malahi by Ibn Khordadbeh. The work is a 3-hemistich panegyric in Middle Persian, but with an Arabic script; none of its music is extant. The poem is as follows: Christensen suggested in 1936 that the text Khvarshēdh ī rōshan () is from a poem that was written and performed by Barbad himself or another poet-musician of his time. The text is found in a group of Manichaean manuscripts in Turpan, Xinjiang, China and is written in Middle Persian, which Barbad would have used. It has four 11-syllable lines and its title recalls the Sasanian melody Arāyishn ī khvarshēdh (). Barbad is traditionally regarded as the inventor of numerous aspects of Persian music theory and practice. Al-Tha'alibi first credited him with creating an organized modal system of , known variously as xosrovani (), Haft Ḵosravāni, or khosravani. This attribution is later repeated by scholars such as al-Masudi and Qutb al-Din al-Shirazi. From these royal modes, Barbad created , and 360 melodies (dastan). The structure of seven, 30 and 360 variations corresponds to the number of days, weeks and months of the Zoroastrian calendar. Farhat notes that the exact reason for this is not known, though according to the 14th-century poet Hamdallah Mustawfi's Tarikh-i guzida, Barbad sang one of the 360 melodies each day for the Shahanshah. Al-Tha'alibi recorded that the seven royal modes were still in use during his lifetime, from 961 to 1039. Further information on the nature of these subjects, theories or compositions has not survived. In her analysis of the historical and literary sources concerning Barbad, musicologist Firoozeh Khazrai stated that "until a new independent source on the subject comes to light, many of these attributions should be