William Dalrymple is a transcender bender

Travelling in the deserts of Sindh a few years ago, I came across the extraordinary music of the Shah Jo Raag Fakirs. These men live together in a Sufi brotherhood in the shrine of Bhit Shah, and are custodians of one of the greatest and most unusual mystical traditions in South Asia. Every day they sing the verses of the greatest poet in the Sindhi language, the 18th- century Sufi master, Shah Abdul Latif of Bhit Shah.

Latif is Sindh’s most revered saint. He came from a relatively orthodox Muslim background but during his youth, on the rebound from a failed love affair, he set off wandering through Sindh and Rajasthan in the company of a group of Hindu sadhus and Nath yogis, a sect of ash-smeared Shaivite mystics.

The experience of travelling with these holy men profoundly altered Shah Abdul Latif’s religious outlook, and his poetry mixes Islamic mysticism with Hindu yogic thought. He died in 1752, and every day since then his music and poetry has been performed by his hereditary fakirs every night in front of his tomb at the shrine where he once lived.

On Friday, there will be a rare chance to hear these amazing monk-musicians in London, at the Nine Lives concert at the Barbican, which will bring together four different varieties of rarely seen South Asian devotional music. As well as the Shah Jo Raag Fakirs, the concert will showcase Theyyam dancers from Kerala, Thevaram singers led by Susheela Raman from Tamil Nadu, and the Bauls of Bengal, led by Paban Das Baul, an electrifying performer who has recorded three irresistible CDs with Peter Gabriel’s Real World label.

It’s the beginning of a year-long world tour to launch my new book, Nine Lives: In Search of the Sacred in Modern India. On the tour bus, as well as the five fakir monks from Pakistan, will be a clutch of Bauls — ganja-smoking tantric madmen from rural Bengal — a "possession dancer" and part-time prison warder from Kerala who is widely believed to be the human incarnation of the god Vishnu; a smoky-voiced Tamil diva who has helped to keep alive an ancient but dying sacred song tradition from the temples of southern India, and an anthropologist of Sufi mysticism who does amazing Jimi Hendrix-ish things with his guitar. It’s going to be an interesting few months.

The story of how I got into this strange roadshow has its roots in a trip I made to Sindh four years ago, in the winter of 2005, working on a Channel 4 documentary on Sufi music called Sufi Soul.

Sindh is a province of dusty mud-brick villages, of white-domed blue-tiled Sufi shrines, and of salty desert scrublands broken, quite suddenly, by tropical floodplains of almost unearthly fertility. These thin belts of green fecundity — cotton fields, rice paddy, cane breaks and miles of chequerboard mango orchards — snake along the banks of the Indus as it meanders its sluggish, silted, café-au-lait way through southern Pakistan to the shores of the Arabian Sea.

The same untameable landscape that has made Sindh so difficult to govern throughout its history has also made it a place of refuge for heretical religious sects, driven here from more orthodox parts of the region. This, and its geographical position as the bridge between Hindu India and the Islamic Middle East, has always made Sindh a centre of Hindu-Muslim intermixing and syncretism, with every kind of strange cult, part-Hindu, part-Muslim, flourishing in its arid wastes.

Much of this took place in the Sufi shrines that are still the main focus of devotion in almost every village here. All existence and all religions were one, maintained Sufi saints such as Latif, merely different manifestations of the same divine reality. What was important was not the empty external ritual of the mosque or temple but simply to understand that divinity can best be reached through the gateway of the human heart — that we all have paradise within us, if we only know where to look.

Many Sufis regarded the Hindu scriptures as divinely inspired and took on the yogic practices of the Hindu sadhus: sitting meditating in front of a blazing fire in the heat of summer or hanging themselves by the feet to recite prayers — a practice that is still performed by South Asian Sufis who sometimes use the hat-racks or luggage rails of trains to hang from.