The tradition of qawwali, originally limited to mausoleums and brotherhoods, has now spread everywhere, carried by Nusrat Fateh Ali Khan -an exceptional performer: Sufi poems and incandescent lyricism. While the Mongols conquered by the sword and oppression, the Sufis attracted peoples through the richness of their culture. During their gatherings, these Sufis listened to the poems of their masters, sung by musicians known as qawwal. Their music, enriched with new literary and musical elements, ultimately became the most widespread musical genre in Hindustani music. Nusrat Fateh Ali Khan's group is the leading proponent of this secular tradition. "As each verse was sung, the emotion-filled audience uttered cries of joy that encouraged the musicians. Their gestures marked the syncopations and they swayed from one foot to the other. Deep silence fell when the singer embarked upon one of his subtle vocal variations..."