It's an irresistible contrast. On the one hand, modern mountaineering superstars with their blogs and sponsorship deals, scrapping with outraged Sherpas on the slopes of Everest. On the other, one of the defining images of the 20th century, the photograph of Tenzing Norgay standing on the summit of the world, a symbol of human courage and resourcefulness.

The obvious conclusion – that in the 60 years since Everest was first climbed greed and ego have hollowed out this once noble enterprise – certainly worried Sir Edmund Hillary in his later years. But last week's events, when three of the world's leading climbers fled the mountain in fear of their lives as an angry mob of Sherpas reportedly threatened to kill them, would have caused Tenzing a wry smile.

Even before setting out for Everest in 1953, Tenzing – as sirdar, or leader, of the Sherpas who would carry loads for the sahibs to supply them on the mountain – had been agitating for better working conditions. When his team were told to sleep on the floor of the British embassy's garage in Kathmandu, Tenzing, who was offered a bed inside, was outraged. Next morning, lacking access to any facilities, the Sherpas relieved themselves in the street in front of the embassy, prompting fury from embassy staff, but offering an eloquent reminder that the Sherpas weren't servants who could be arrogantly dismissed.

Even before the war, the diaries of Everest pioneers are full of observations about the pride and resourcefulness of Sherpas and how, when travelling far from home with expeditions, they wouldn't hesitate to defend their honour, even if it came to blows.

Nevertheless, news of Sherpas and climbers fighting has sent shock waves through the mountaineering world. The three mountaineers – Ueli Steck from Switzerland, Italy's Simone Moro and Briton Jon Griffith – had been moving without ropes at more than 23,000ft. At the same time Sherpas were laying fixed ropes for guided climbers to use on their way to the summit. As the trio crossed these ropes on their way towards their tent at camp three, an argument broke out, with the Sherpas claiming that one of them had been hit by ice dislodged by the westerners, an allegation they denied. Later, when the climbers returned to camp two, a much larger group of Sherpas attacked them, punching and kicking them and throwing rocks. Other foreign climbers intervened, calming the situation so that the three could escape to base camp.

Views are split between admiration for Sherpas, and the infectious joy that they take in life, and concern that the commercial exigencies of climbing Everest, which can cost $65,000 (£41,000) a head, don't really square with the freedom of the hills. What has been missed in reports of this hypoxic mêlée is a much broader story, and a rather more inspiring one. The inexplicable passion among a small, wealthy European elite for exploring the mountains of the Sherpa homeland, together with the Sherpas' ability to cope with altitude, gave these people a chance to escape difficult lives herding yaks or carrying loads for traders.

If you're looking for a good example of the consequences of this unlikely journey, then the multistorey Sherpa Adventure Gear shop in Kathmandu is better than most. Inside its air-conditioned interior, with its racks of colourful outdoor equipment, you could be forgiven for thinking you'd been transported to Seattle – which is, in fact, where the company is based. Its owner, Tashi Sherpa, is the nephew of Gyalzen Sherpa, one of those who worked on Everest in 1953 and the last of them to die, in his early 90s, a couple of years ago. "People were very poor," Gyalzen recalled in later life. "There were few houses. Most Sherpas worked as coolies transporting loads for the few rich traders that lived here. The expeditions changed that."

Mountaineering was the catalyst that changed for ever Khumbu, Gyalzen's homeland below the slopes of Everest. It also extracted a terrible cost. More than 230 people have died on Everest, and a third of them have been Sherpas – the latest, Mingmar Sherpa, at the start of last month.

Out of friendship and gratitude, Hillary and his friends founded the Himalayan Trust, a sustained development effort that saw schools and health centres built and an airport constructed at Lukla in the mid-1960s. That airport is now the hub of a booming tourism industry. Since Nepal's civil war ended in 2006, the number of trekkers and climbers visiting this small region has surged each year to stand at 35,000.

With so much of their business in Kathmandu, many Sherpas now spend much of the year there and send their children to the best private schools in the region. Working for expeditions still offers a way for Sherpas to move up the economic ladder. But for the educated, new avenues are open to them as doctors and airline pilots – and, more recently, as airline owners. One of Nepal's big two domestic airlines is owned by a Sherpa.

"Of course, there's been a cultural impact," Tashi Sherpa says. "But you have to weigh it from both sides. Do you still want Sherpas to be the same, uneducated, simple folk? No. We want our children to be educated to go out into the world. I'm the classic example. I had the benefit of the best education my parents could give me."

Sherpa Adventure Gear has had a real economic impact on the lives not just of Sherpas but other groups in Nepal. It employs, either directly or as subcontractors, more than 1,400 Nepalis, most of them women. It also runs an education programme for poorer Sherpa children. It's hard to think of another group that has travelled so far so quickly.

Tashi Sherpa, born in Khumbu and now a US citizen, sees the world from both perspectives. He agrees that westerners can have a romantic view of Sherpas. "But do you say progress is evil? No. How can you deny Sherpas electricity? Or access to computers and the internet? We need these things to face the pressures of the modern world. Does it change Sherpa culture? Of course. But there are ways for us to assimilate the best that the west offers and mix it with our own unique heritage."

Despite this progress, only a fraction of Nepal's 150,000 Sherpas live in Khumbu and there are many pockets of desperate poverty. Rebecca Stephens, the first British woman to climb Everest, is chair of the UK branch of the Himalayan Trust. "We continue to support the running costs of projects in Khumbu," she says, "but there are places where Sherpas live that are like Khumbu was when Sir Ed started."

Stephens cites the district of Taplejung in eastern Nepal, location of the world's third-highest mountain, Kangchenjunga. George Band, part of the 1953 team, made the first ascent of Kangchenjunga with Joe Brown in 1955. When he went back for an anniversary trek, he realised the work done in Khumbu was now needed elsewhere – and for a broader ethnic mix of mountain people.

"The Sherpas are heroic figures in my eyes," says Stephens, who reached the top in 1993. "Without them I wouldn't have got up there. They are extraordinarily caring. But Everest has changed enormously in the last 20 years."

Jon Griffith, the British climber who was one of the trio who came under attack, spoke of the frustration many Sherpas feel about how they are treated on Everest, but Tashi Sherpa is not convinced. "People talk about 10 or 20 years of frustration. I don't think there's any frustration. If anything, Sherpas are a lot better treated now then they were 10 years ago. We have a voice. Along with development and education, we have a clearer understanding. It's no longer that idea of the simple native."

He points to the decision of the international body that represents mountain guides to admit Nepal's mountain guides. It's an illustration of the steady rise in the ability of Sherpas, not just to carry loads but to set ropes and look after clients in a hostile environment.

Sherpas are also gradually taking control of how the mountain is managed. This was the immediate cause of the friction last week. Sherpas may now have the technical skills to become guides, but mountaineering is still for them a commercial activity whose ethics are largely meaningless.

Professionals like the Swiss Ueli Steck and the Italian Simone Moro, whose use of the word "motherfucker" in Nepali started the spat, have no need for fixed ropes or Sherpa support. That must seem an annoyance, even a threat, when you're hard at work earning a living.

Moro, who has climbed the mountain four times, said Everest has seen an influx of younger, more outspoken Sherpas. That self-confidence matches a broader development in Nepalese society, the rise of the janajati movement, janajati meaning indigenous ethnic groups. Subjugated under the monarchy, these groups, including Sherpas, are finding their voice. They have also grown up in an atmosphere of demonstrations and political chaos.

"There's a great sense of each one's worth now," says Tashi Sherpa. "The way things were for the last 200 years isn't going to continue. There are going to be some serious changes in the next election and hopefully it will be for the better. We want change, we're the marginalised ones and we want social inclusion. These are noble sentiments. Hopefully the system won't corrupt our people too."

The Himalayan Trust is holding an Everest anniversary afternoon event on 29 May at the Royal Geographical Society (himalayantrust.co.uk)