The band Indian Ocean will not take offense if you call its music “fusion.’’ For one thing, the Delhi-based foursome is too laid-back to worry much about labels. And it’s true that at first glance Indian Ocean’s approach summons up echoes of Orientalist jazz-rock projects from the ’70s, with their setup of guitar, bass, and drum kit plus tablas, and their long, improvisation-heavy songs that weave Western melodic elements into a texture of Indian rhythms.

But this is no Mahavishnu Orchestra or Shakti. For one thing, all four members are Indians who grew up and still make their home in the country. Not all of them trained in Indian classical music, but they take from it not just the rhythm cycles but a lot of the same source material, be it folk music from India’s many rich regional traditions or the devotional poems of the medieval mystic Kabir.

Most of all, Indian Ocean, who will play at the Middle East on Sunday, are resolutely modern, of this moment: From their emergence in the early 1990s to the point where they now have something of a cult following in India, their career tracks neatly with the country’s economic opening, the rise of its now-potent middle class, and enormous transformations in its media and culture marketplace.

In this dynamic context, says drummer Amit Kilam on the phone from a tour stop in Seattle, labels have grown pointless. “Fusion is a generic term now,’’ Kilam says. “Everything is fusion. Bollywood is fusion. What we should call our music is something even the four of us do not know.’’

What they do know is that their blend is catching. As they have grown older - band founders Susmit Sen and Asheem Chakravarty met as students in the mid-’80s, and when Kilam joined in 1994, bassist Rahul Ram already had a PhD - Kilam says their audiences have grown not just larger but younger as well.

The band has become a fixture on the Indian college circuit, playing at annual festivals held at the top universities and technology schools where India is nurturing its new business and science elite. They’ve also broken into film music - the fastest path to notoriety in movie-obsessed India - even though their sound has nothing to do with stereotypical Bollywood kitsch.

“India is a younger nation now, and young people are more willing to change,’’ Kilam says. “So if age was a factor for us, I think it’s been taken over by the fact that India has gone in a happily new direction. In Bollywood now we see different kinds of films, and younger directors taking chances.’’ Those include musical chances, he says. In the old model, a small number of singers monopolized soundtracks, and music directors followed a standard template for the choreographed routines. “It made for a fair amount of repetitiousness,’’ Kilam says.

But after the title track of Indian Ocean’s 2003 album “Jhini’’ was used in a movie, producers began to reach out. In 2004 the band wrote the soundtrack for “Black Friday,’’ a critically acclaimed film about the series of terrorist attacks and ensuing riots that took place in Mumbai in 1993.

Kilam says they had heard a lot of “horror stories’’ about writing for Bollywood, but the producers gave Indian Ocean complete freedom in scoring the film. And with its success, new doors opened wide. “The reach of Bollywood is tremendous,’’ he says. “We started getting calls from other cities, smaller cities where we had never played before.’’

The fast transmission of Indian cultural production through satellite TV and the Internet also means that Indian Ocean has grown a big fan base in the Indian diaspora. On previous US tours, the band has frequently played for large, mostly Indian crowds. They are regulars at fund-raising events held for NGOs that provide social services back home.

But now, Kilam says, they are looking to break out of the immigrant circuit and into the mainstream. Their current tour has mixed both types of events, including college and club gigs and a world music festival in Albuquerque. At the Middle East, they’re hoping to draw a good share of non-Indians. “We are reaching out to more and more people,’’ Kilam says. “You could say it’s an experiment.’’

They are also keeping themselves stimulated by taking up new instruments - Ram has added the saxophone, Kilam the clarinet - and imagining new ways to flesh out a sound that is already layered and alluring. Let the audience grow as it pleases, Kilam says, reverting to a classic musician’s axiom. “We still perform pretty much for ourselves,’’ he says. “We like it, so we do it.’’