[And here is what Sachs has to say about Bharata's ancient text the Natya-Shastra, which he agrees could be as early as the 4th century BCE and about… - Curt Sachs

The roots of music are more exposed in India than anywhere else. The Vedda in Ceylon possess the earliest stage of singing that we know, and the subsequent strata of primitive music are represented by the numberless tribes that in valleys and jungles took shelter from the raids of northern invaders. So far as this primitive music is concerned, the records are complete or at least could easily be completed if special attention were paid to the music of the ‘tribes’…[There are] hundreds of tribal styles…

The oldest preserved style, the classical Sino-Japanese Bugaku dances […are…] of Indian origin, and Chinese and Japanese music on the whole were under Indian influence in the second half of the first millennium A.D. And yet the most typical trait of Indian music, its sophisticated rhythmical patterns or tālas, had no chance in the East. In 860 A.D., someone wrote a treatise on drumming in China, with over one hundred ‘symphonies’ which doubtless were Indian tālas; but nothing came of this, and not one of the Far Eastern styles has preserved the slightest trace of such patterns. The three rhythms used in Tibetan orchestras, and kept up in percussion even when the other parts are silent, are obviously not Far Eastern, but deteriorated Indian patterns. The elaborate polyrhythm of Balinese cymbal players that Mr. Colin MePhee has recently described is not Far Eastern either.

When we read in Bharata's classical book of the twenty-two microtones in ancient Indian octaves, of innumerable scales and modes, and of seventeen melodic patterns and their pentatonic and hexatonic alterations, we realize that music at, or even before, the beginning of the first century AD was by no means archaic. Indeed, there is no reason to believe that India's ancient music differed substantially from her modern music.