 Raga is the soul of Indian classical music. It is the comprehensive and imaginative mode of musical expression. There are twenty-two shrutis out of which seven notes are collectively known as saptak or an octave. There are two styles of music in India. The Hindustani music of North India and the Karnataka music of the South. India's preoccupation with musical instruments began thousands of years ago. The earliest records are found in the cave paintings of Bhimbetka in central India and also in the South. The oldest stringed instrument in India found in the Indus Valley civilization sites was the harp in the shape of a bow. Veena is the generic term for all stringed instruments. The Veena had a horary antiquity. According to Shiv Purana, Shiva invented the Rudra Veena. A sleeping Parvati, his consort, gave him the idea of its form. It is said that Amir Khusru, the Persian poet and scholar, added three more strings to the Indian Tri-Tantri Veena with three strings as its name indicates. This came to be called the sitar. India has a long tradition of wind instruments. They are of two kinds, flutes and reed instruments. The great flutist Pannalal Ghosh had his finger joints cut to be able to produce the lower notes of a raga. Smaller or shorter flutes held at times vertically are used for tans, the faster passages and higher pitches. Percussion instruments are among the oldest. Drums are divided into different categories on the basis of their shape and the way they are held while playing. The tabla is the main percussion instrument of North India and dates back to the 18th century. The Ekthara of Bengal and Urissa, called Gopiyantra, is associated with the Baals, the itinerant musicians of the region who are dedicated to Vaishnavite worship and Sufi modes of expression. They go from village to village, singing. The Gopiyantra is at times accompanied by the Kamak.