I FIRST MET TSERING in 2003. Walking around one night with a friend who specializes in finding ultra-obscure ethnic restaurants, I was doubtful we'd spot one here on SoHo's chic Crosby Street. But then he dragged me up a couple of steps into a windowless place not much bigger than a walk-in closet. The aromas of curry and black tea enveloped us. Ten or 12 men had formed a line, more like a scrum, craning and peering over one another's shoulders. The place had a small sign that read LAHORE and a menu featuring pakoras, goat biryani, and other Central Asian comfort food.

My buddy and I were talking about mountains we wanted to see one day—K2, Everest—when we heard a quiet voice behind us.

"You guys climbers?"

We turned. Compact and sturdy, the man wore a battered Casio altimeter watch and black jeans. He had high cheekbones and dark, imploring eyes.

"I overheard you talking," he said politely. "I am Sherpa." He pronounced the e like a long a and gave a slight roll to the r: share-pa. "I worked as a trekking guide. I moved here five, six years ago. My name is Tsering."

"All the cabdrivers come here," Tsering told us as we ate samosas by the counter. Kazakh, Bangladeshi, Kashmiri, Ladakhi—they drink high-octane tea, hit the restroom, and stock up on sweet cakes and lentils before heading back into the maelstrom of New York by night.

"So ... you know of Sherpa Tenzing Norgay, right?" Tsering asked as we got up to leave.

"Yeah, of course," we said.

"Tenzing Norgay was my grandfather."

It was surprising enough that a grandson of Tenzing Norgay, the legendary Sherpa who conquered Everest with Sir Edmund Hillary in 1953, was driving a cab in New York. But Tsering went on to tell us that there were perhaps a hundred Sherpas working as cabbies in the city, many of them former guides.

Their presence, I learned, was part of a larger diaspora. Though roughly 150,000 Sherpas still live in Nepal, northern India, and Bhutan, perhaps more than 5,000 have left—heading to England, Australia, and Germany (where one, Ang Jangbu Sherpa, flies a Boeing 767), but mostly to America. Over the past decade Sherpas have been streaming to the U.S.—to San Francisco, Seattle, Salt Lake City, Portland, Oregon, Washington, D.C., and above all New York. The city's Sherpa community has become the largest outside of the Himalayas, with around 2,500 members, most employed legally through yearlong work visas, harder-to-get green cards, or rare lottery visas, 50,000 of which are awarded randomly to applicants from developing countries each year.

Tsering's wife, 36-year-old Nima Phuti Sherpa, is a former trekking guide. His close friend Ang Galgen Sherpa, 35, once had his own trekking company, Sherpa Expedition, in Kathmandu; now he drives a cab. Dawa Sherpa, a 45-year-old who has worked on expeditions up 26,906-foot Cho Oyu, is a cabbie, too. Three-time Everest summiter Kipa Sherpa sells jewelry from a stall on Canal Street, while "Speed Kaji" Sherpa (five times up Everest; six 8,000-meter peaks; one Guinness world record for fastest Everest ascent, since topped) moves furniture in Queens. Pasang Namgyal Sherpa, a 57-year-old mountaineering veteran, works for Landmark Wines, in Chelsea, with his brother, Temba, also a former guide. Their sister, Nima Diki Lama, runs a popular Himalayan restaurant, the Yak, in Jackson Heights, Queens.

None of those Sherpas still guides, but others living around the U.S. have kept a foot in the business. Tashi Gyalzen Sherpa, another of Tsering's friends, runs a small travel agency in Queens called Himalayan Adventures. In Salt Lake City, Apa Sherpa—who completed his 17th Everest summit last May as part of the two-man SuperSherpas expedition—cofounded the Karma Outdoor Clothing Co. His climbing partner and fellow Utah resident Lhakpa Gelu Sherpa, a 13-time summiter, currently holds the speed record from Base Camp to the top (10:56:46). Last winter, Lhakpa ran the coffee stand, Peak Java, atop Snowbird ski resort.

But why would a Sherpa leave the kingdom of yaks and stupas for Super Size Me America? For some, like Nuru Lama Sherpa, who worked at Goldman Sachs after graduating from Harvard University's Kennedy School of Government, it's because of the educational opportunities. For most, it's politics and economics. A distinct ethnic group that migrated 500 years ago from Tibet into Nepal's Solu Khumbu Valley, the Sherpas spent centuries working as traders and raising livestock, but over the past 100 years they've become famous worldwide for their work as porters and guides on almost every Himalayan expedition ever launched. Mountaineering was never a sufficient economic base for all Sherpas, though, and in the past 17 years political turmoil has racked their homeland.

First, the Marxist-flavored People's Movement, which emerged in Nepal in 1990, wrested away some of the power held by Nepal's Hindu monarchy. Amid the discord, the charismatic Maoist leader Prachanda carved out a heavily armed following; up until a cease-fire was called in May 2006, some 13,000 Nepalis were killed in bombings, raids, and skirmishes between government forces and the Maoist rebels.

Combine that with a sharp drop in Western tourism to the region after September 11 and the situation for many Sherpas has become precarious. A top mountaineering Sherpa can earn around $3,000 or $4,000 per expedition, working two trips a year if he's lucky. But that pales in comparison with the kind of money Sherpas can make here, some of them earning enough to send thousands of dollars home every year, according to the United Sherpa Association of New York. And they don't have to worry about getting crushed by a falling serac.

Bob Peirce, an 83-year-old former trekking guide from Portland, Oregon, has helped a number of Tibetan and Sherpa newcomers get settled in the U.S. "Even the Sherpas here say it: It's a migration," he says. "The main reason they come—and they talk about this—is to make money. Working in a restaurant or a convenience store is probably more reliable than trekking jobs."

Some observers, including Sir Edmund Hillary himself, see clear dangers in the trend. "I know a lot of Sherpas are now based in New York, and that's fine," says the 87-year-old, "but I just hope that they don't completely lose their culture."

"Going to work somewhere in New York, or anywhere in the U.S., would be very, very tempting," Hillary says. "The only thing is, for every Sherpa who goes to New York and earns money and sends it home, the vast number are good people who are really needed in the Khumbu. I'd certainly hope that they all come home, because they have so much to give to their own communities."

Tsering feels those losses but says he had to make the change. "I miss mountains and I love mountains," he told me. "But what I don't like there is the economics. I don't blame the mountains, you see. But if there are no tourists, no Westerners that come to climb mountains for the trekking, for expeditions, we are dead."