A father and his sons sit in the desert, barely looking at one another as their hardened fingers press on the dark teak necks of their instruments.
As they draw horse-hair bows across steel strings, the pulsating energy summons the sound of a train accelerating. Suddenly, the pace eases: the musicians pause, preparing themselves before all at once they move the drawn bows staccato-like across the strings: the train, the performance suggests, rapidly approaches, puffing away until the piece is brought to crescendo. The "train" has arrived. And quiet descends upon this desert scene once more.
Ashu Sharma and Ankur Malhotra spring to their feet. They have been recording and filming this entire musical session but had not realised they would hear such an impassioned performance. They grin at one another. "That is the thing with recording in the field," says Malhotra. "You never know what you are going to get. This project could be endless. Every time you go out, you discover more."
For more than two years now, the two schoolfriends have been filling every spare moment travelling to remote villages in the north of India with their video camera and microphones and recording traditional music they fear is at risk of forever being lost.
Inspired by the folk historian Cecil Sharp, who toured the British countryside by bicycle in the early 1900s, and Alan Lomax, who recorded country, blues and folk musicians in America during the 1930s and 1940s, the pair's dream is to create an archive of recordings not just from Rajasthan and Gujarat, but from across the country.
The two blues fans, who went to school in Delhi, also want to ensure the musicians they are recording benefit directly from their work. Already, the pair have produced three albums of traditional songs and arranged several concerts. They say that half of all profits go directly to the artists. They have also uploaded more than 50 videos on to their website, which anyone can access. Their record company is called Amarrass, "Eternal Essence", and they stress the need to publish authentic tunes, rather than some impresario's assumed idea of what the outside world expects Indian folk music to be.
They are hoping the project will one day at least break even, but for now they are driven by their ferocious love of the music and the friendships they have developed with the musicians of the desert. The project is financially supported largely by the travel agency Sharma set up in Delhi when he was 19 and embarking on a different career.
Slowly building relationships with the artists has been no small undertaking. The duo's endeavour has led them to drive hundreds of miles across scorching territory, endure dust storms that have besieged villages and forced them to cancel recordings and, on the part of Malhotra, juggle another life as a part-time professor in the US. On one occasion, the battery in their car cracked and, rather than risk not being able to start the engine again, they drove 18 hours non-stop back to Delhi.
It is a blisteringly hot spring day in the town of Jaisalmer, not far from the border with Pakistan, and in his workshop, the musician and blacksmith Mohan Lal Lohar is getting out his bellows to work up a fire. While he can make and play several instruments, he is best known for producing the morchang, an instrument widely used in some regions of India and known in the West as a jew's or jaw harp.
As his wife, Gigi Devi, pumps on the leather bellows, Lohar and one of his two sons hammer in unison on a glowing piece of metal. A simple morchang can be made in hours; a more elaborate design could take a couple of days. Watching and listening to the trio – the two men bashing on the metal, Devi pumping the 100-year-old cowhide bellows – is itself like witnessing a musical performance.
Sharma and Malhotra, both 37, have already recorded Lohar playing the morchang, but today they are here to record him playing the algoza, a double-barrelled flute with the left-sided instrument operating as a drone and the right used to perform the melody. Beeswax is used to fill stops on the drone to alter the pitch.
Playing the flute requires circular breathing, something Lohar claims took him two or three years to master. "If someone played for one-and-a-half hours every day they could play OK at a beginner's level after one or two years," he says. "After about 20 years, you are pretty good.
"There has never been an institute for folk music," he adds. "It has always been something passed from father to son and sustained by people's interest." He explains that much less traditional music is being played these days and one of the reasons, he believes, is increased urbanisation. People are moving into the towns, away from the villages, away from the goatherds and the way of life that sustained traditional music. The growth of tourism, he says, has provided an outlet for some musicians who play "traditional tunes" for foreign visitors in upscale hotels, but not enough to make up for the overall decline.
Such a fall-off has a direct impact on families such as his, who make their living producing instruments. "We have to hustle more," he concludes.
Beneath the metal roof of his workshop, as a couple of goats look on, Lohar starts to play. The tune is melodic, delicate and enchanting, and his long, thick fingers flutter on the right of the two flutes. He might be a goatherd, playing for his animals.
But what is most unnerving about his performance is that here in the Thar desert, in the very heart of south Asia, his tune sounds like nothing other than a Scottish reel. Sharma, Malhotra and Lohar are barely surprised by such an observation. They are among many who believe the nomadic musicians of Rajasthan may have been responsible for transporting an entire body of music and tradition westwards, feeding into Roma gypsy, flamenco and Celtic music. Professional ethno-musicologists say there is no conclusive evidence to prove this, but many musicians from various cultures say they believe there is a link that is clear to them when they play together.
Last year, Sharma and Malhotra, whose record company also comprises friends Ravneet Kler and Avirook Sen, organised a series of concerts in Delhi to which they invited traditional musicians from Rajasthan and celebrated traditional West African performers from Mali, including the 21-string kora player Mamadou Diabate, and guitarist and singer Vieux Farka Touré and his band.
The highlight of the event was the final performance of the second night when everyone took to the stage and jammed together, the desert sounds of Africa and India blending seamlessly.
Whatever the truth about the purported westward migration of the musicianship of Rajasthan, what is beyond doubt is the complexity and richness of the culture that has developed. Even now, some of it, in particular the "kinship practices", are not fully understood.
The musicians of western Rajasthan, centred around the district of Barmer, belong to two Muslim castes, the manganiyar and langa. Traditionally, the two groups have performed music for a community of "patrons", a word that imperfectly refers to a relationship in which the musicians receive sponsorship, money and often payment in kind from the more dominant group. (The langas have always performed for Muslim patrons, while the manganiyars perform for the Hindu rajput caste.)
"A lot of the songs would be about traditions," says Malhotra. "At a wedding of a patron, there would be one song performed for guests arriving, another performed when guests were leaving. There would be songs for when the woman leaves for her husband's village."
Not surprisingly in this desert environment, water is a recurring theme. There is an entire sub-genre of songs relating to so-called paniharis, women whose job it is to get water. "There are lots of songs about women collecting water – women taking clay pots and going to the well."
Shubha Chaudhuri is an ethno-musicologist and director of the American Institute of Indian Studies at Gurgaon, a satellite city of Delhi. The private organisation houses an archive of traditional music from across the country. Chaudhuri believes the traditional music of Rajasthan is robust – she points out that many traditional musicians have toured the US and Europe – but accepts that the repertoire being performed for most listeners is becoming smaller. She refers to it as "erosion".
A co-author of the exhaustive Bards, Ballads and Boundaries: An Ethnographic Atlas of Music Traditions in West Rajasthan, Chaudhuri says that between 10 and 20 songs are played all the time at concerts in India and abroad and she believes the performers feel that an audience of the general public – unlike their traditional patrons – would not want to hear the more "authentic" songs.
"I have been arguing against [the musicians] dumbing down. There are still a lot of discerning audiences out there. Otherwise, how would traditional Indian classical music survive? It's their perception," she says. "My attitude when I am with them is to try to make them sing songs they no longer normally sing."
Sharma and Malhotra, who readily admit to being amateurs, believe the situation is more dire. They point to musicians such as Lakha Khan, a celebrated player of the sarangi, a traditional instrument, and the uncertainty about its future. "He is the last grandmaster of that instrument in his community. He is struggling to persuade his sons to pick it up," says Sharma. "If they do not, all that knowledge will be lost. The tradition will not slowly die off; it will die an instant death."
Yet, like Chaudhuri, they believe the authentic music can survive if a large-enough audience is made aware of it. Unlike their hero Alan Lomax, who struggled with desperately heavy equipment and aluminium plates, digital technology has handed them a much simpler way of recording and publishing the music. Adds Sharma: "The music is good. There are enough people to sustain it, but we need to make those people aware of it."
Sharma's SUV bounces over the railtracks on the way to the village of Hamira, in the Jaisalmer district of Rajasthan. In the back-seat is Sakar Khan, a celebrated performer of the kamancha, a bowed instrument that has 17 strings, three of gut and 14 of steel. Sakarji, as he is referred to, is aged 76, wears a splendid white moustache, and has been playing since he was a boy. This year the Indian government announced they were giving him the Padma Shri, a civilian award, for his services to folk music.
Malhotra and Sharma had been planning to record Khan and his musician sons in their home, but there has been a death in the village and such an endeavour would be frowned upon. Instead, they set up on mats on a small hill a short distance away, overlooking a small lake. There are six separate microphones as well as their video recorder.
Sakarji is to perform with three sons – Ghewar, Feroz and Darra – and other assorted musicians from the village. "We are musicians by caste. My father, my grandfather, we all trace ourselves back," says Ghewar. "I started playing the kamancha when I was 14. For the first two years I did not sleep [at night], just played. I would practise all night and then fall asleep at dawn. I would watch my father playing. It took me five years to master it."
And why did he choose the kamancha? "The sound is so special and otherworldly. It's like a lullaby. It can put a baby to sleep. It has a comforting sound."
The first tune they play is an emotional song, performed when a bride-to-be leaves her family's home to go to the house of the husband. The sister of the bride grabs the hem of her sibling's sari. "I won't let you go," say the lyrics. "Please stay here with me. As I look at you putting your feet in those shoes, my eyes are filled with tears because you are leaving."
Having warmed up with this plaintive number, the musicians are ready for something a little more lively, a self-penned composition that relates to their recent history. Until 1958, Jaisalmer had no paved road to connect it with the outside world. Ten years later, the authorities decided to go one step further and extend the railway line from the town of Pokhran. Sakarji was asked to perform at a ceremony to welcome the first train and he wrote a special piece of music, designed to imitate the sounds of the engine getting nearer and nearer.
With Sharma and Malhotra giving the signal, the musicians get under way, building slowly to a grand climax suggestive of the engine and its carriages drawing up at the platform.
Malhotra and Sharma are happy with the first take. Yet Sakarji is not overly optimistic about the future of the music that he and his sons play, and he dismisses many of the songs played by some performers as being "like nursery rhymes". "Our songs are not dead yet, but I see that at some point they may be," he says, as the sun starts to slip from the sky. "The kamancha should stay alive and we should be able to teach it to our children. We hope that we can do this."
For more information, and to hear a recording of 'The Train', visit amarrass.com. Andrew Buncombe is the Independent on Sunday's Asia correspondent