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Deep in the Gobi Desert, Joyce Morgan tracks a Silk Road pioneer and his remarkable discovery.
The camel man drops to his knees. Until now Mr Liu has shown no sign of tiring. Indeed he has belted out song after song as he has walked ahead of me through the towering dunes of the Gobi Desert.
And then he begins burrowing. There's nothing to mark this spot other than a solitary bush a few metres away. But minutes later he uncovers from the sand a black plastic bin liner. He pulls out of it a camp chair. Then another.
After just a few hours, I'm relieved to have something more forgiving to sit on than a saddle lashed between the twin hairy humps of a Bactrian camel. In the desert, where there's rarely even a scrubby bush to lean on, a battered folding chair is a luxury.
I realise how the loss of a camp chair must have irked the trailblazing desert traveller Aurel Stein, the British-Hungarian explorer and archaeologist whose footsteps I'm tracing, when he dropped it in this region a century ago. An honest local found the chair and sent it across the desert to a friend who forwarded it to Britain. It eventually reached the explorer, by then ensconced at Oxford University, and he continued to sit in it.
The well-travelled chair would have reminded Stein of the 30 months he spent digging in the desert, during which time he stumbled on the Silk Road's most precious gem - a hidden library in a Buddhist cave a few kilometres from where my camel has just deposited me.
On a late autumn day, Mr Liu has my camel packed when I arrive at his village on the edge of Dunhuang. The oasis in Gansu Province, in China's far west, was once one of the Silk Road's most vital lifelines. We wander through shady lanes where corn ripens and cotton is ready for picking. Mounted on the camel, I dodge most of the apples that hang heavily from the trees. The fertile, irrigated strip abruptly ends. The desert looms - and creeps closer every year.
To reach it Mr Liu leads us through the village cemetery. Spread across a couple of kilometres, the graves are marked by brick cones about a metre tall. Some are surrounded by elaborate walls, all built on sand. This reminder of fleeting existence seems especially resonant in the face of an enduring, advancing desert.
Mr Liu is unfazed by this amble through the dead centre of Dunhuang, although my other companion on our overnight desert trek, a young Chinese-Dutch woman, is uneasy. Her grandmother would not approve of traversing a graveyard for fear of attracting evil spirits, she explains.
The Gobi is said to be full of them. Marco Polo, who ventured here in the 13th century, related local legends of fatally bewitched travellers. "When travellers are on the move by night and one of them chances to lag behind or to fall asleep or the like, when he tries to gain his company again he will hear spirits talking and will suppose them to be his comrades," the Venetian explorer warned.
"Sometimes the spirits will call him by name; and thus shall a traveller oft-times be led astray so that he never finds his party. And in this way many have perished."
With the graveyard behind us, we plunge into the ocean of sand. The dunes rise up to 300 metres, their sharp ridges highlighted by the golden afternoon light. Having come here to experience some of the heat and dust Stein endured, while researching a book about his Dunhuang journey, I now understand why he referred to the desert's "alluring splendour".
Autumn's first chill is in the air. Soon the temperature will drop below freezing and overnight trips into the desert will cease. The season for camel-riding is short. Spring, which brings warmer temperatures in March and April also brings fierce sandstorms that have buried entire caravans. Summer temperatures can soar to 50 degrees.
From the camels' bags, Mr Liu produces fuel and a cast-iron pot. We eat a bowl of noodles by the fire's fading embers. Clouds have suddenly rolled in, and there are no stars.
Mr Liu is a man of few words - "let's go" and "coffee?" is about the extent of his English - and without sufficient fuel to sustain a fire, an early night beckons. I retire to my tent where I hear no spirits, just intermittently flatulent camels.
I wake in the night to a sound I did not expect to hear in a region where the annual rainfall is approximately zip. I doze off wondering whether a waterproof tent is a priority in the desert. I have my answer in the morning - although the sand is wet, I'm not. I have experienced something Stein, the father of Silk Road exploration, did not. In all his writings on his desert travels - during which he nearly died of thirst and camped in cold so extreme his moustache froze in his sleep - there's no mention of desert rain.
"Coffee?" Mr Liu asks. He reburies the camp chairs, loads my camel and helps as I inelegantly clamber aboard. I ask what the beast is called. "No name," he says. I rework a tune as we make our way back through the sands: I've been through the desert on a camel with no name.
In the distance we see a train of camels, like a line of ants, heading for the dunes above Crescent Lake on the edge of Dunhuang. The natural lake, sky blue amid the golden sands, has enchanted Silk Road travellers for centuries. Set in a hollow between the dunes, its existence seems to defy nature. Why doesn't the moving sand fill the lake? How does it retain its crescent-moon shape?
The lake is one of Dunhuang's most popular sites. Yet with its camel rides and sand tobogganing, it is no longer the tranquil place Stein once sat beside and contemplated as his final resting place.
The main reason to visit the oasis is to see the nearby painted Buddhist caves. The Mogao Caves, or Caves of the Thousand Buddhas, are a network of sacred grottoes hand-carved into a cliff face about 15 kilometres outside Dunhuang. They contain the world's greatest gallery of Buddhist art.
Set in a river valley, the caves, with their precious artwork, are today protected by metal doors. It is no longer possible to wander unattended, as Stein did. A guide unlocks a door and shines her torch on a wall. Rows of painted Buddhas adorn every centimetre. On the ceiling celestial musicians pluck instruments so detailed they have revealed much about the music of the past.
Nearly 500 caves remain, created between the 4th and 14th centuries, each different in size and decoration. Some are tiny meditation cells, just big enough for a lone monk. Others have high ceilings and were able to hold a couple of hundred worshippers.
The guide leads the way to a massive sleeping Buddha in a coffin-shaped cave. The Buddha is surrounded by statues of devotees, their faces reflecting their different reactions to the Awakened One's passing from earthly life into nirvana - some mournful, some joyful, some with Caucasian features, perhaps based on the early visitors from afar.
But the cave all visitors want to see is not full of magnificent murals or statues. It is the hidden Library Cave, scene of the Silk Road's most remarkable discovery.
In 1900, a Chinese monk clearing sand from a meditation grotto spotted a crack in a painted wall. Behind it lay a small ante-chamber crammed from floor to ceiling with thousands of paper scrolls. All had been perfectly preserved for 1000 years within the dark, dry cave.
Most were sacred Buddhist texts but there were also painted silk banners and secular documents, including a "morning after" apology letter for getting drunk. The jewel was the world's oldest printed book, the Diamond Sutra. Printed in 868, the scroll - ironically about life's fleeting illusions - is 500 years older than Gutenberg's famous Bible.
The scrolls still filled the cave when Stein arrived in 1907 during an epic overland journey from India by yak, camel, horse and foot in search of lost Buddhist civilisations. He controversially convinced the guardian monk who found the cave to part with thousands of his treasures and took them to London.
Most, including the Diamond Sutra, are now in the British Library.
Of all Stein's discoveries in a lifetime of indefatigable travel, nothing would eclipse this. The now-empty Library Cave, with which Stein's name is inextricably linked, held an unparalleled record of life along the Silk Road.
Why the tiny cave was sealed remains a mystery. Fear of Muslim invaders advancing east, some say. Others say the cave was a storeroom for scrolls no longer needed by the surrounding Buddhist monasteries.
But why the caves were created is clear. Near Dunhuang, the Silk Road split in two to skirt the rim of the feared Taklamakan Desert, the vast almond-shaped eye in the centre of present-day Xinjiang Province. The two routes met again 2200 kilometres west, in Kashgar.
Between Dunhuang and Kashgar lay the Silk Road's most dangerous terrain. Starvation, thirst, bandits and ferocious sandstorms were among the ever-present threats to caravans laden with rubies, musk, jade and silk. Travellers prayed at the caves before embarking or gave thanks for safe deliverance.
Though the caves contain Buddhist images - on walls, ceilings, altars - there are secular images here, including a caravan being attacked by bandits and even of a figure defecating. Rich merchants helped pay for the caves, and their images are painted in some of the caves, like sponsors' logos today.
Dunhuang remains a cosmopolitan oasis. In its bustling night market, chefs grill fish and mutton over glowing coals for travellers who these days arrive by plane or train. Trinket stalls sell statues of apsaras, the flying celestial creatures painted throughout the caves, silk scarves printed with their image and, inevitably, stuffed toy camels. In a jewellery shop, an assistant attempts to squeeze a jade bangle of a white "mutton fat" - the most prized of jades - over knuckles that resist her bone-crushing efforts.
There's bone-crushing of a more sustained sort next morning when I venture before dawn by mini-van along unsealed roads into other desert sites where Stein camped. After a couple of hours, the rolling dunes surrounding Dunhuang have given way to a pancake-flat baked clay.
Soon we will reach the rocky outcrops known as "yardangs", carved by the prevailing wind and all facing the same direction. The wind is indeed howling as I walk among the massive shapes, where I am dwarfed by natural sculptures that resemble giant sphinxes or whales.
The wind throws up so much grit that after barely an hour I feel thoroughly sandpapered. I'm relieved to rejoin my driver to continue the bumpy ride to the furthest extension of China's best-known symbol.
The Great Wall conjures images of massive stone fortifications. But this section is made of material seemingly more flimsy: layers of straw and packed earth. Built to keep out invaders and safeguard the Silk Road trade, this wall has survived 2000 years in the dry desert.
So, too, has the nearby Jade Gate. From the clay fortress, with sweeping views across a barren plain, no caravans could pass undetected nor, presumably, untaxed. The Jade Gate was effectively an ancient customs and immigration office and once marked the edge of China. It was named after the precious stone that caravans passing under its arch conveyed from Khotan (now Hotan), the great Buddhist kingdom across the Taklimakan Desert from whose rivers jade was - and still is - collected. But its location had been forgotten until Stein pinpointed it in 1907.
Near the Jade Gate, Stein found a postbag lost en route to Samarkand in 313. Within was a letter from the furious wife of a merchant who had abandoned her in Dunhuang. "I would rather be a dog's or a pig's wife than yours," she wrote.
Accidentally dropped like Stein's camp chair a century ago, the letter resurfaced with its fury still burning.
I wonder whether, a few centuries on, someone might pull from the sands Mr Liu's bin liner and marvel at its contents. Dead men might not tell tales. But dead deserts do.
Joyce Morgan is the author, with Conrad Walters, of Journeys on the Silk Road (Picador, $34.99), published on July 1. www.journeysonthesilkroad.com
Air China has a fare to Dunhuang from Sydney for about $1200 return including tax. You fly non-stop to Beijing (12hr), then Dunhuang (3hr 15min); Melbourne passengers connect in Sydney. Australians require a visa.
The author flew to Dunhuang from Shanghai and returned by train, via Lanzhou and Xian, which was booked at the Dunhuang railway ticket office. The two-day journey in a soft sleeper carriage costs $US138 ($130) for a lower berth.
The author arranged a camel trek and one-day minibus trip to the Jade Gate and surrounds through John's Information Cafe, Mingshan Road, Dunhuang. Most hotels will organise trips.
The Silk Road Dunhuang Hotel, about four kilometres south of town on Dunyue Road, resembles a traditional fort. Its rooftop bar is a good place to sink a beer at sunset. Double rooms cost from $78.
Dunhuang Binguan, 14 East Yangguan Road, is a comfortable high-end hotel with double rooms from $110.
Feitian Hotel, 22 Mingshan Road, is a mid-range hotel in the centre of town with rooms from $40.