Mumbai: If AR Rahman's Sadda Haq is on loop on your music system, you have a small group of locals from Dharamsala to thank.

It was initially supposed to be a song that plays in the background whenever Ranbir Kapoor exhibited his rockstar mannerisms. But perhaps even unexpected by Imtiaz Ali, the director of the film, Sadda Haq, Ethe Rakh has already become mighty popular.

One needs to thank a group of music aficionados in Dharamshala for this.  Says a source, "Imtiaz was supposed to shoot this as any other regular number, in fact a song sung by a bunch of chorus artists. But during the process of shooting when the locals of Dharamsala heard the song, they all ganged up to convince Imtiaz to convert this into a live song."

Not surprisingly, most locals there who are still fighting to free Tibet could relate to the intention behind Sadda Haq. Adds the source, "The song speaks for anyone who is asking for their rights. So especially those groups of people who have been fighting for a cause over so many years felt like it was something they have wanted to say for all these years.

The locals stepped up and participated in the shoot and involuntarily became part of the song. They used to shoot for 10 hours straight without any money, because they felt like it was their song."

So the song, which to be shot at one stretch in Dharamsala, then came down to Delhi and Mumbai, where the director shot with local rock bands too. "Ranbir himself was pretty surprised with the massive crowds who used to gather when the song was played.

In fact, he made sure he took notes from some local Mumbai rock bands, to understand and adapt to their style of singing." The last time we saw a song catch up at such pace was Salim-Sulaiman's Chak de India and A R Rahman's Rang De Basanti before that. Not sure if Sadda Haq will have a similar impact, but for now it's hitting all the right chords.