Qawwali is a form of Sufi Islamic devotional music originating from South Asia, and notably popular in the Punjab and Sindh regions of Pakistan; in Hyderabad, Delhi and other parts of India, especially North India; as well as the Dhaka, Chittagong and Sylhet divisions of Bangladesh.
It is part of a musical tradition that stretches back for more than 700 years. Many Pakistani website have great collection of Islamic qawwali mp3 download facility.
Originally performed at Sufi shrines or dargahs throughout South Asia, it gained mainstream popularity and an international audience in late 20th century. Qawwali music received international exposure through the work of the late Pakistani singers Nusrat Fateh Ali Khan, Sabri Brothers, and Aziz Mian largely due to several releases on the Real World label, followed by live appearances at WOMAD festivals. Other famous Qawwali singers include Pakistan's Fareed Ayyaz & Abu Muhammad, Abdul Habib Ajmeri, Rahat Fateh Ali Khan, Badar Maindad,Nusrat Fateh Ali, Rizwan & Moazzam Duo, the late Amjad Sabri and Bahauddin Qutbuddin and Aabida Parveen.
Source of Information is Wikipedia