(CNN) - In the vast, snowy Mongolian countryside, nomadic herders are combing through the hair shed by their yak.
It used to be that they would throw away the hair -- until Nancy Johnston persuaded them it could be the key to preserving their traditional way of life.
Mongolia is one of the world's largest supplies of cashmere, which is made from Mongolian goat hair. But due to global demand for cashmere, the number of goats in Mongolia has risen from 5 million in 1990 to 19.3 million in 2009.
And the proliferation of goats has been damaging the environment.
"Their little feet really trample the ground and don't leave the fragile terrain to restore itself," Johnston explains. "There's more animals than the land can support and as a result, 90% of Mongolia's land is at risk of permanent desertification."
While part of the reason is the increase in livestock, the fragile, dry country has also suffered from significant climate change.
But Johnston thinks she may have a solution. She believes the Khangai yak -- an indigenous wild species found in Western Mongolia -- could preserve the country's landscape, because they're gentler on the fragile steppes, and help save the herder families' nomadic lifestyle.
Johnston has been helping herders to switch from producing cashmere to yak wool, and using their yak wool for her high-end British knitwear label Tengri.
'The biggest problem with yak is its name'
Johnston says yak fibers are warm and as soft as cashmere, and while using yak wool isn't new in itself, she says there has never been a global demand for it -- mostly because there's a perception that yak is not a valuable fiber.
Robin Deas, a textile technician who worked with Tengri's wool at Scottish hosiery mill House of Cheviot, says the biggest problem with yak is its name.
"It's a simple three-letter word, which can be construed in all sorts of ways. But it has very good properties," he says.
"These hardy little beasts have to live through considerable temperatures and their fiber is genuinely luxurious. The thing is being able to promote it in a way that gives the luxuriousness of what it is."
From Mongolia to London
Within three years of launching, Tengri's yak fabric was being stocked in some of London's finest stores, like Savile Row tailor Huntsman -- which offers clients bespoke jackets. Some of its products sell for upwards of £11,000 ($15,300).
Exclusivity is part of Tengri's appeal, and part of the company's mission is to spread profits along the entire supply chain, from herder to tailor.
Tengri says it pays premium prices to the herders for their fibers and shares any profits with the nomadic community as part of its "fairshare" business model. It now works with a co-operative of 4,500 families in Mongolia.
"I knew I had to give it the highest value on the market, especially if I was going to make a dent in the livelihoods of people at the start of the supply chain," Johnston says.
"While not everyone can afford it (yak wool), it's important for customers to see the value of paying fair trade prices," she adds.
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