"[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 which he tells us that it] "testifies to a well-established system of music in ancient India, with an elaborate theory of intervals, consonances, modes, melodic and rhythmic patterns". ... "Bharata's text was probably rehandled as early as antiquity, and it may confirm the idea that Bharata himself wrote his treatise much earlier" ... [He also tells us that this text establishes that it represents a stage where the] "slow transition from folk-song to art-song, from hundreds of tribal styles to one all-embracing music of India […] had long ago come to an end"."