Iranian musical art comes from a very ancient tradition. It was only after the Islamic conquest that one have been able to trace its evolution.
The Abassyde princes were very fond of music and of poetry (750-1258). They encouraged scholars to compile and to develop previous musical concepts. Persian music and its instruments reached a very high degree of perfection and refinement and was propagated all over the Arabian world.
On one side, the monarchs encouraged the development of Iranian musical schools. On the other side, this development was hindered by Muslim orthodoxy which admitted only devotional chant in the ritual. Under such conditions, music became more intimist and had to discover a more refined timer for the instruments.
Under the dynasty Qajar (1785-1925), the notion of Dastgagh became more and more important in Iranian repertoire and now it's and essential basis of Iranian music.
Dastgagh is a modal system based on a very complex scale with special intervals. The repertoires of Dastgahs are constituted by pieces called Gush-s.dd The most important modal systems are Chour Mahur, Homayun, Segah, Chehargah, Docheti, Nova, Rast Pandjgah, Abar-ata, Bayate-tork, Afshari and Bayate-esfahan.
These systems are entirely applied by musicians but improvisations play an important role. The singers give us a very personal interpretation and exploit all the subtleties of the Persian art of singing. ...