Once upon a time, sometime in the 13th century, a red-cloaked saint from Uch Sharif wandered into the desert kingdom of a Hindu ruler, Raja Sadharan. He invited the raja to embrace Islam but was unceremoniously turned away. The queen of the kingdom, childless and anxious, had heard of his holy powers, and she sought him out in secret, begging him to pray for her.

You will have a son, the saint assured her. He will be Muslim.

Needless to say, the king wasn't too pleased when his son arrived into the world with the kalima on his lips, so he had him packed into a box of sandalwood – channan in local parlance – and dispatched him into the deepest bowels of the desert. But this was a child of destiny; the universe conspired to keep him alive. A donkey brought him food and water every day, says one legend; another version insists it was a mother deer. Soon people also began flocking to him, to partake in his grace and seek his blessings. Eight hundred years have passed and they still keep coming. On this particular Thursday, they will come in the thousands.

Asmatullah Shah peers through the windscreen of our speeding car like an excited child. "Look, everyone in that trolley is so dressed up!"

"Those sacks of wheat and those goats! Someone's mannat (prayer) has been fulfilled."

"Ah, they are coming on camels. Just like old times."

We are on our way to visit the desert saint: Shah, a teacher of Seraiki language at one of the oldest colleges in Bahawalpur, two poets – a man from Bahawalpur and a woman from Dera Ghazi Khan – and me. Every Thursday, for seven weeks at the start of spring, the environs of Channan Pir come alive; devotees celebrate all night and disappear in the morning. This particular day, the fifth of the seven Thursdays, is so popular that it is an official holiday in the whole district of Bahawalpur. As a result, the road to the shrine, running through the market town of Yazman and then through chequered fields, is clogged with traffic of a startling variety: tractors and trolleys, motorcycles and minivans, camels and cows – and donkeys.

Shah hasn't visited Channan Pir in a while. A long time ago, his parents made this pilgrimage: they came to the saint to pray for his birth. Years later, they returned with little Asmatullah in tow, bringing bags of wheat and flour and a lamb. The trip was different then – rows of bedecked camels on what used to be dirt tracks and a continual rippling of bells, rather than beeping horns. Modernity has dulled the culture, he notes sadly.

All this used to be desert once. Indeed, barring Uch Sharif, Bahawalpur during the Mughal era was so barren that imperial revenue documents dismissively referred to it as berun Panjnad or outside Panjnad — that was its only reference point. When the Abbasis established their state, they built a sprawling series of inundation canals: according to an 1871 British engineer's report, 45 canals of various sizes tapped the Sutlej, Chenab and Indus rivers, comprising some 2,176 kilometres of engineering works; another 4,800 kilometres of cultivators' ducts branched out from the canals, carrying the water ever further. As academic Richard Barnett points out, even as early as 1835 in Khanpur, 37 kilometres away from the

Indus, a lieutenant in the Bengal Engineers reported seeing flooded rice fields stretching all the way to the horizon: "… green was almost the only colour that met the eye in an expanse of many miles," he wrote in clear awe. The most transformative of the engineering works was still to come, however — the Sutlej Valley Project, built during the 1920s, involved the construction of three barrages still in use today; it ensured a perennial supply of water. And so it is that the shrine of Channan Pir, once marking a spot so deep in the desert that a king thought it possible for someone to remain lost there forever, is now perched on its very edge, bordered on one side by a sea of green inching further and further into Cholistan.

Shah twists in his seat and looks back.

"You know, this is almost entirely a Punjabi area — but everyone at the mela will be Seraiki. Except maybe a few urchinswho'll come for a stare and a laugh. You wait and see."

We are passing through rural settlements known as chakook, built mainly for settlers who moved to the state of Bahawalpur to cultivate land made available by an expanding irrigation system. Some of the first to come were Sikhs and Bishnoi Hindus, in the mid-1860s, followed by Muslims from princely states in eastern Punjab and what now constitutes central Punjab in Pakistan. It is difficult to ascertain the exact number of migrants: on the one hand, Barnett notes that the population of Bahawalpur doesn't really seem to increase very dramatically between 1871 and 1951; on the other, according to figures cited in Re-Thinking Punjab: The Construction of Siraiki Identity and attributed to The Civil and Military Gazette, abaadkaars (settlers) accounted for 42 per cent of the population, Seraiki-speakers for 37 per cent and mohajirs (migrants) for 21 per cent in 1952. In any case, migrants who came as settlers or in the wake of Partition, remain a major sticking point in the politics of the area; in demographic terms,

Bahawalpur division, only slightly different from the Bahawalpur state of yore, is currently almost equally divided between the speakers of Punjabi (45.82 per cent) and Seraiki (46.59 per cent). Urdu speakers account for nearly four per cent. And in such a scenario, the chak – as distinct from the Seraiki mauza – has become a symbol of historical wrongs for many Seraiki nationalists. One poet even used it as a motif in his work, playing on its second meaning (bite) to illustrate the injustices meted out to the indigenous population.

'Mein trisa, medi dharti trisi, trisi Rohi jae, mekon akh na Punj Duriyai' ('I am thirsty, my land is thirsty, the Rohi desert is thirsty, don't label me as a dweller of the land of the five rivers'), this same poet, Javed Aslam, wrote in another work.

What makes his poetry enigmatic is the fact that Aslam was born to Urdu-speaking parents.

Apart from teaching Seraiki, Shah is also working on his doctoral thesis, an exploration of the evolution of Seraiki dohra or couplet. His respect for Khwaja Ghulam Farid is so profound that he blushes when he speaks of him. An ardent nationalist, he wears his politics on his sleeve. That morning, though, he is quite literally wearing it around his neck. An ajrak is slung proudly across his shoulders.

"A sajrak," he corrects me, pointing towards its colour, the classic blue of a Multani tile. "You know, ajrak actually originated from this region, near [the town of] Karor, then travelled down to Sindh. Last year, some of our Seraiki intellectuals decided it was time to reclaim it as sajrak."

He pauses, then adds: "The name didn't catch on. So we are calling it the Seraiki ajrak now."

Earlier, a colleague of Shah, a teacher of statistics who compiled a lengthy tome on the workings of the Bahawalpur state, narrated a story. Many years ago, a learned man called Maulvi Abdul Haq with familial roots in Gujrat used to teach Arabic and Persian to the children of the state's finance minister. The minister was so taken by Haq's erudition that he offered him a job in his ministry. Haq accepted and steadily worked his way up

the ranks to the top. "When he died, his son inherited his position," said the statistics teacher, pursing his lips. This son, Akhtar Ali, whose own son Khalid would go on to become a celebrated Urdu fiction writer, was in charge of settling all the emerging arable land in the state.

It sounded like a wonderful migrant story to me, an illustration of one man's destiny-defying dynamism — but to Seraiki nationalists, it serves as the starting point for something far more insidious: the influx of Punjabi settlers. "The trouble with most settlers is that they still have links with where they came from," one nationalist tried explaining, choosing his words carefully. "They don't integrate. They retain their original loyalties. And that causes friction."

It is a sentiment felt by many people. A Seraiki-speaking lawyer based in Bahawalpur who professed to not particularly care for the nationalist cause did say it angered him to hear settlers, who had been living in the city for generations, claim they couldn't comprehend a word of Seraiki. Shah's colleague, the statistics teacher, said his own father joined government service as a junior clerk and retired as a senior clerk; around him, better connected colleagues rose to posts as high as that of district commissioner. Who you are determines who you know, argue nationalists — it can boost you or set you back in life. It can only help to belong to an ethnicity that dominates – or has dominated, in the case of Urdu-speakers – so many of the country's institutions: the army and the bureaucracy, federal and provincial politics. And so, when the car trundles off the tarmac and begins inching through the throng of cows and camels and humans towards the shrine of Channan Pir, only to be yelled at by an irate – and admittedly Punjabi – officer of the Punjab Police, perhaps it is a little understandable that Shah doesn't view him merely as a bad-tempered man but as a symbol of ethnic oppression. Perhaps the policeman sees Shah as some sort of a symbol too.

"See how they speak to us," says Shah, seething with resentment.

At Channan Pir, though, it isn't possible to remain angry for very long. The green dome of the shrine, ordinarily immediately visible against the rolling sand, is surrounded by hundreds of tents; after all, the real party starts at dusk. Men form circles

and perform the jhumar dance. Many are wearing the original ajrak, I realise with a sudden pang of sympathy for Shah — it seems that it may take some time for sajrak to catch on.

The desert saint has followers far and wide but nowhere more than in Cholistan itself. Nomads have brought their best animals along — plump cows and goats and camels with intricate designs carved on their hide and names scrawled on their long necks. Bijli. Kabootar. Jhoolay Lal. There is also an Abdul Waheed among the camels, reminding me of the clever childless Cholistanis trying to pass off their animals as their offspring. The donkey that kept baby Channan Pir alive and fed hundreds of years ago is also buried here; a small shrine has been erected for him and, with great reverence, nomads bring their donkeys there to pay respect.

The shrine of the pir itself is teeming with people, mostly men, a blur of bodies pressed against each other. Occasionally, a determined woman elbows her way through the crowd to distribute her share of tabarruk, or sacred sweets.

The shrine is conical in shape, a bit like the top of a circus tent, and the sweets come rattling down towards the grasping hands of devotees. From time to time, people break from the crowd and clamber onto the shrine itself in an attempt to press their eyes and lips to its pointed top.

They are swatted away by the harried men from the government department overseeing the shrine.

There is an old tree in the compound. Channan Pir's mother, the erstwhile queen of the land, is said to be buried under that tree. The branches that shade her grave are bowed by colourful threads; they represent the hopes and dreams of thousands of devotees. There is also the odd Coca Cola bottle wrapper on a branch, tied just as meticulously as other threads — someone, perhaps, ran out of string. Many people who come here pray for a child, just like the queen once did. I wonder how many, if any, of the threads on this bright hopeful tree are wishes for a plot of land.

A few days ago, a disgruntled nationalist had been complaining that the only area of the mazaar where you might find non-Seraiki speakers was the market adjoining the shrine — settlers just saw the festivities as an occasion for commerce, he lamented. As we walk through the market, a winding muddle of stalls selling bangles and plastic dolls and prayer mats, I ask Shah if he thought this was true. He nods, then points towards a clumpy paan stain on the ground so large it is almost a puddle. According to him, Seraikis rarely eat paan.

"The outsider has reached here," he says bitterly.

Identity politics is a curious thing. Two major developments occurred during the 1970s. A literary conference was held in Multan, the first All-Pakistan Seraiki Literary Conference in 1975 — and a language, long considered a dialect of Punjabi, referred to by colonial administrators as Wuch and Mooltani and Jatki and Southern Lahnda and Western Punjabi, was standardised and given a formal name. Many reasons are given for it having been clumped with Punjabi for so long: as the poet-academic Nukhbah Langah argues, it was perhaps because large parts of what Seraiki nationalists call vasaib had been under the influence of Ranjit Singh or possibly because there were no physical barriers such as mountains between the Punjabi and Seraiki regions — or perhaps because, while making their classifications, the British had neglected the folk tradition and oral culture so crucial to this language. No one knows where the word Seraiki originated from or why it was agreed upon unanimously, though many link it to the Sindhi word siro, meaning north. All the same, it was a stunning achievement: millions of people across a vast stretch of land were suddenly given a common identity marker and a new consciousness. Of course, some saw it as yet another demonstration of the narcissism of minor differences, the notion that precisely those communities that live next to each other engage in constant feuds and ridicule.