Over time, musical offerings of dervishes and sheikhs in the presence of the devout at these shrines, usually impromptu or on the occasion of Urs, gave rise to musical genres like Qawwali and Kafi, wherein Sufi poetry is accompanied by music and sung as an offering to a "murshid", a type of Sufi spiritual instructor. Today they have become a popular form of music and entertainment throughout South Asia, with exponents like Nusrat Fateh Ali Khan and Abida Parveen taking their music to various parts of the world.