If you take a train from Kolkata to Shantiniketan in West Bengal, chances are you'll encounter these wandering minstrels called Bauls. They sing songs about universal harmony with only an ektara — a one-stringed instrument — for accompaniment. It's a far cry from the sort of music that Nucleya makes. He embodies a wholly modern, electronic aesthetic, which, again, is the polar opposite of the Carnatic strains that emanate from TM Krishna's voice. The point is that India is a land of musical VIBGYOR. Songs change colours across every border. And that's what London-based sarod player Soumik Datta has tried to capture in a new documentary he's hosted, which will premiere on BBC World on January 25 and is called Rhythms of India.