Her eyes riveted to the canvas, Wulan meticulously applies colour to an image of the Buddha, using pigments made of crushed pearls, turquoise and agate.

The 34-year-old is one of dozens of students at a school in Lhasa learning the medieval Tibetan art of "thangka" -- minutely detailed paintings depicting Buddhist deities or symbols, usually on cotton canvas or silk scrolls.

But she is not Tibetan. Ethnically Mongol, she moved 2,500 kilometres (1,600 miles) to embark on seven years of studies.

Beijing's forces took over Tibet in 1951 and the Communist government reviles the exiled spiritual leader the Dalai Lama, but the region's traditional religious art is now increasingly being embraced by outsiders -- including from China's Han ethnic majority -- as both buyers and producers.

"Thangkas are captivating a growing number of people," said Wulan. "Traditional cultures are more and more recognised in China, which wasn't always the case in the past, during the economic boom."

In their heyday centuries ago thangkas had patrons and practitioners in Nepal, Bhutan, Tibet and northern India, and in 2009, UNESCO added them to its list of the intangible cultural heritage of humanity, calling them "an integral part of the artistic life of people" on the Tibetan plateau.

Now there are more than 100 apprentices -- including some Han Chinese, the country's overwhelming ethnic majority -- at Wulan's Danba Raodan school, who get free tuition in return for helping their teachers with their paintings. The students spend 10 hours every day learning how to trace figures in pencil, wield delicate paintbrushes and apply pigment to canvas.

- Turbulent priest -

The revival comes after a turbulent past -- the Dalai Lama fled Tibet in 1959 after a failed uprising against Chinese rule and the ravages of Mao's Cultural Revolution laid waste religious tradition and iconography as zealous Red Guards -- including Tibetans -- sought to destroy the "Four Olds": customs, culture, habits and ideas.

"Beyond the destruction of artworks and monasteries ransacked, looted or burned, a lot of the expertise was lost. Many teachers disappeared or were in prison and could not train young people," said Amy Heller, a Tibetologist and art historian based in Switzerland.

"Even after the Cultural Revolution, it was difficult. The censorship had been such for 10 years that people were reluctant to bring out their thangkas, for fear of being denounced."

Many Tibetans accuse Beijing of wanting to dilute their culture and the Dalai Lama says Tibet is the victim of "cultural genocide".

Beijing considers the Himalayan region an integral part of its territory -- a view disputed by the Tibetan government in exile and some scholars -- and retorts that it ended serfdom and brought development.

The issue can find its way into art.

In 2014, Chinese tycoon Liu Yiqian paid a record $45 million for a 15th-century thangka tapestry believed to have been a gift from a Chinese emperor to a Tibetan Buddhist leader.

At the time, Liu said: "If you look at it from the perspective of politics and diplomacy in ancient China it is... of great importance, because 600 years ago Tibet was a part of China already."

- 'Spiritual hole' -

Once only made by artisans attached to Buddhist temples and monasteries and painstakingly produced according to strict rules, the creation of thangkas is now open to anyone passionate about the art.

The vast majority of the Danba Raodan students are still Tibetans, but when it opened its doors in 1980 there were only 20 thangka painters in Lhasa, said its director Tenzin Phuntsok, who inherited it from his father.

"Today there are a thousand. And nationally, about 10,000," he said.

Each painting requires between one month to three years of work, depending on its size and complexity.

And while thangkas were traditionally offered to monasteries or sold to Tibetan families, the art has now secured a new, lucrative audience -- Chinese collectors.

"They come from the big cities of Beijing and Shanghai, and are becoming more numerous," said Tenzin Phuntsok.

As interest grows, prices have soared, rising 10 percent a year according to the specialist Tiantangwu gallery in Beijing.

"The thangka of a novice teacher is already worth several thousand euros," added the director, whose own works sell for nearly 200,000 yuan ($30,000).

The older generation of painters "do not necessarily welcome this commercialisation", acknowledged the 31-year-old, but said: "As a young person I find it inevitable. The main thing is to find a balance between the tradition and the market."

Some specialists warn of wider risks.

After decades of frantic economic growth and materialism, "Chinese sense a need to fill a spiritual hole with religion", said Wang Jingyi, professor of art at Taiwan Normal University in Taipei and market analyst.

"And they are drawn to Tibetan Buddhism, which has more colourful art than what you find elsewhere in China."

But Chinese collectors' "frenzy" for thangkas was "not necessarily beneficial for relations between Han and Tibetans", he added, as Han-owned galleries sometimes reaped huge profits from the works of Tibetan painters.

"Ultimately, these are religious items," he said. "If they are too commercialised, they will lose their religious identity."