The traditional music of Iran is based on the radif, which is a collection of old melodies that have been handed down by the masters to the students through the generations.
The preservation of these melodies greatly depended on each successive generation's memory and mastery, since the interpretive origin of this music was expressed only through the oral tradition.
The radif contains several different dastgāhs which are distinguished from each other by their relationship of note intervals and the form of the movement of the melodies within them.
The shahed moves when we modulate between principal goushehs, and this movement creates a new sonic space.
One of the most notable tar players and repertoire of Mirza Hossien Gholi's radif was Ostad Ali-Akbar Shahnazi, who was the son of Mirza Hossien Gholi and was the first tar player to record the long radif memorized by heart.