The growth of Indian classical music has been a major force of India’s cultural unity. Most of the words and themes of the Indian classical music have been derived from Hindu mythology but some of the greatest masters of this music have been Muslims. The Kitab-i-Nauras, a collection of songs in praise of Hindu deities and Muslim saints, was written by a seventeenth century ruler Ibrahim Adil Shah II. Both in vocal and instrumental music two main classical styles have evolved—Hindustani and Carnatic. These two styles have many things in common and each has a variety of forms. Besides classical music, Indian people have developed rich traditions of folk music.