A new mountain road is bringing big changes to Nepal's prime trekking territory. It's a lifeline for locals but what impact will it have on tourism? Amar Grover reports

Walking through a broad river valley of bleached grey stones, I paused. Soaring cliffs of loose rubble gave way to steep slopes of scree. Higher still rose dark crags and bluffs, jagged ridgelines and finally the snow-dusted peaks of the Himalayas serrating a brilliant blue sky. Raw, stark beauty, I thought – much as I had 22 years ago when walking in this very spot.

Then I heard noises I would never have heard back then: a tooting horn and the asthmatic wheeze of an engine. A rickety 4WD sped past, full of passengers eyeing me curiously, a plume of dust rising behind it. A sign at its rear said "Muktinath Express". A minute later, the landscape regained its pristine splendour and I walked on.

An hour behind me lay Jomsom, the closest thing this area of Nepal has to a main town, with a long-established airstrip and modest facilities. A few hours ahead stood the village of Kagbeni. For three decades this part of the Himalayas has been prime trekking territory. Some of Nepal's classic treks – the three-week Annapurna Circuit and the shorter, overlapping Jomson trek – pass this way via Muktinath, Jomson and the mighty Kali Gandaki valley down to Pokhara.

Yet, while the grand scenery remains immutable, the region is experiencing major changes. The catalyst is a new road. Years in the making, in 2008 Jomsom was finally connected with Pokhara and the lowlands through the Kali Gandaki. The road continues from Jomsom to Kagbeni where one short spur climbs east to Muktinath. Another heads due north into Mustang, a peculiar, almost time-forgotten enclave of Tibetan culture that protrudes into Tibet.

In trekking-tourism circles, particularly among Western visitors, this has caused concern. The almost instinctive reaction – mine included – is one of dismay. A road! How could they? Most of it lies in the Annapurna Conservation Area (ACA), Nepal's largest protected area with its most popular trekking routes. In the local media, virtually all references to it are couched in shades of regret. Myopic bureaucrats, you might hear, are ruining Nepal's tourism just as it had emerged from years of Maoist-inspired turmoil and unrest.

When I first trekked the Kali Gandaki – among the world's deepest valleys, which slips between the giant peaks of Annapurna and Dhaulagiri – a road seemed utterly implausible. Virtually everyone walked (the Jomsom flight from Pokhara was for the rich and foreign). The experience was unforgettable in a way that poor-yet- beautiful places often are, as though one refracts sharper, profounder light on to the other. People lived on the edge of their steep terraces, rivers and cliffs – and a few impoverished families seemed on the edge of life itself.

Yet, there was little grinding poverty. For centuries, this valley was a well-known trade route between the Indian subcontinent and Tibet. Tibetan salt and wool were traded for lowland grain, and some locals prospered from customs tariffs or by running inns for merchants and pilgrims. When China closed the Tibetan frontier after a popular uprising in March 1959, the trade stopped abruptly. Then trekking tourism arrived in the 1970s and revived the fortunes of many local families.

Tim Greening, co-founder of trekking specialist KE Adventure Travel, says: "Not so long ago, many of us were predicting the [road would spell the] end of the full Annapurna Circuit, but this hasn't happened." KE and some other operators have altered their trekking route – mainly south from Jomsom – to follow the valley's eastern side, where there are fewer villages and less frequently used trails. Trekkers still cross to the opposite roadside and stay or eat in its venerable "teahouses", or inns. "Not one client has grumbled about the road in their feedback," he adds.

Kirsty Parsons, of Mountain Kingdoms, which has been sending clients to the area since 1987, echoes the view that most clients seem happy with the year-old alternative route that avoids the road. Many though, including innkeepers, still expect that inevitable changes will eventually curtail trekking tourism. The road, as Greening puts it, has not taken "full effect".

"The road is rough and dangerous in parts," an innkeeper in Jomsom told me. Think of a bridle track – unmetalled of course – prone to landslides that block it or send it careering into the river. Countless side ravines and gulleys have to be crossed without bridges and culverts. No one here expects this day-long, 50-mile drive to be open during the monsoon. At other times, much depends on the weather and how promptly it can be repaired. For vehicles – small buses, 4WDs, pick-ups and the odd car – it remains a tenuous route with relatively little traffic. For now.

"Almost everyone wants it," a Nepalese traveller in my group told me one morning as we watched our bags loaded on to mules for the days ahead. It was autumn and the road was blocked again. Jomson's fleet of green minibuses (with "Save the Environment" emblazoned on their rooftop luggage racks) were going nowhere. A handful of 4WDs were taking the strain, heading down as far as a landslide where transport waited on the other side.

"It's necessary for our economic development," he continued. "Cargo rates by air cost about Rs40 [about 30p] per kilo, by mule it's around Rs20, but by truck it's Rs5 or Rs6. In your country, who lives without roads? You see?" Indeed, I did. I also saw women selling bags of the locally famous apples that were introduced in the 1960s as a cash crop to try to alleviate the lost Tibetan trade.

Yet, real progress here was always hindered by transport difficulties that have made Indian, and even Chinese apples cheaper in the lowlands. That seems set to change. Mushrooms, too, may follow if initial production and sales can be maintained.

"And then there's Muktinath," the man added. Later that morning, several more "Muktinath Express" jeeps passed by, most filled with Hindu pilgrims heading for the lofty village and its famous pilgrimage site. They come from the farthest corners of Nepal and India to a small temple to bathe in frigid water emerging from the mountainside through 108 spouts. Its spur road was coaxed by the lure of religious tourism since relatively few have the stamina to come here on foot, or the money to simply fly in and walk from Jomsom.

Hours later, I strolled into Kagbeni, a medieval-looking place of tunnel-lanes and tightly clustered mud-walled houses overlooking fields of millet and a narrow neck of riverbed. Today, this is the formal gateway to Mustang, once known as the Kingdom of Lo. Fearsome 18th-century Gurkhas persuaded the Lobas that they were better off with Nepal than Tibet, while its physical remoteness kept the place in a time warp.

The first Western visitor only arrived in 1950. For three decades from 1961 the place was entirely closed to outsiders. Its opening has been cautious – trekkers require a special, and pricey, permit which is available only to organised groups. Mustang still has a rajah, or king, whose official, largely ceremonial role has become vaguer now that Nepal's own monarchy has recently been extinguished. Change has been glacial but the road from Kagbeni is closing in on its extraordinary walled capital, Lo-Manthang.

Before I entered Kagbeni's 15th-century monastery's prayer hall with its 19th-century dust, a monk whipped out his mobile to call another for the keys. Behind its burgundy walls lay dim rooms with swirling frescos of Buddhas and demons, cosmology and mythology. "Life's much easier now," said the monk, "there's more food, it takes less time to get things or get out." It was a view I heard daily on the five-day trek to Lo-Manthang.

Next morning, we climbed above Kagbeni to join the rough track heading north by the Kali Gandaki. From a distance, it looks driveable but up close you see the problems: unstable conglomerate, scree, washed-out gullies. By Tangbe village, just four miles beyond, it seemed no vehicle had come this way for months. At Chhusang, two miles further, the track stopped altogether so we followed the vertiginous, centuries-old paths that hugged near-barren mountainsides tinged mauve, red and brown.

The daily rhythm was simple – bed-tea, brought to our tents pitched in fallow fields or camping gardens alongside inns, followed by big breakfasts. We'd hike for much of the day on trails that looped round and above the main canyon-like valley, and pause at little village teahouses for lunch. Alongside their whitewashed houses with panda-eyed windows, Lobas threshed grain with horses and winnowed it with baskets. The dazzling Annapurna range gradually receded behind us, and each of the nine passes we crossed marked another exhilarating milestone in the approach to Lo-Manthang.

It was just after Ghami village, a day's walk from the capital, when we saw a tractor and trailer full of villagers bumping down a 13,000ft pass. A motorable track was recently pushed south from Lo-Manthang, a logical extension of the road that opened in 2002 between the capital and Tibet, barely 10 miles apart. Despite difficult terrain between the dead ends at Ghami and Chhusang, locals firmly believe they will be joined within a few years. Meanwhile, even our group could reap the benefits as Chinese beer and Coke halved in price in just one day's walk.

Local people pressured the government for a road and everything is cheaper now, explained some of the town's young men, referring to imported items like clothes, shoes, blankets, thermos flasks and batteries. I was talking to them in the main square by the rajah's palace, a many-windowed white-washed building that was palatial more in size than design. "But," chipped in one, "the food's usually poor quality, or really out of date." He chuckled: "And we prefer Nepali rice, much better taste."

At lunch, word came that the king would, as he often does, grant us an audience. Armed with cream-coloured locally bought scarves, we filed into a modest salon and presented them to the rajah one by one. We sat and sipped warm buckthorn juice; questions were invited. What, I asked, did he think of the new road.

Raja Jigme Bista, 25th direct descendant of Mustang's first ruler, smiled and answered carefully through his translator. "The king doesn't like it. He fears for his culture, increased crime, pollution – and more westernisation." He sounded somewhat out of step with his people and rather more in tune with the trekkers who may, in time, decide they'd rather not hike by a road.

Compact Facts

How to get there

Amar Grover flew to Nepal as a guest of Qatar Airways (0870 389 8090; qatarairways.com/uk), which connects to Kathmandu twice a day via Doha from London Heathrow, Gatwick and Manchester. Fares cost from £576. He travelled on the Mustang – The Forbidden Kingdom tour with KE Adventure Travel (01768-773966; keadventure.com). The next departures for this 14-day trip are on 24 April and 25 September, and the land-only, fully inclusive price is £1,345 per person, plus a restricted area fee of $500 (£310). Trip code MUS.