Indian music encompasses some of the richest musical traditions of the world. India's musical history begins in the second millennium BC with the advent of the Vedic period. The Samaveda, one of the sacred four Vedas ("four books of knowledge"), comprises the world's oldest notated melodies. Beginning the second century AD, complicated theoretical system developed, and the important raga principle was established. Islamic influences brought about the division, about 1200, of Indian music into the northern and southern systems that continue today.
A raga is identified by a particular combination of musical phrases that gives it its distinctive melodies character. The pitches in a raga may be represented in the form of ascending and descending scales. Many of the standard phrases are so well known that the informed listener is able to tell immediately which raga is being performed. Regardless of whether the raga performance is vocal or instrumental, a drone (a sustained tone of fixed pitch) is invariably heard in the background. The drone instrument is usually the tambura, which has a long neck and four strings tuned to the basic tones of the raga. Magical power is attributed to some ragas, and many ragas should be performed only at certain times of the day on night or during specific periods of the year.
The other basic element of Indian art music, the tala, is a rhythmic cycle containing of fixed number of beats. Talas five the rhythmic foundation of melodic structure and are performed on drums. Within the sequence of beats the drummer plays rhythmic patterns associated with a particular tala. The drummer may repeat the sequence more than a hundred times in a single performance. The tala divided into subsections, marked by accents on their first beat, the most important accent occurring on the very first beat of the tala cycle.