For millennia, hardy travellers have relied on a surreal oasis in the dunes, says Jim Eagles.
As our small train of camels wound its way between the giant sand dunes of the Gobi Desert, my throat was feeling parched and my water bottle was nearly empty, yet there was still no sign of the promised oasis.
Then suddenly, against the harsh white of the sand, came a glimpse of green which quickly transformed into a patch of trees. Surely water was near.
When we reached the greenery, our leader ordered the camels to sit - which they did with the usual grumbling - so we could dismount. Then he pointed beyond the trees to a gap between two giant dunes and said: "Yueyaquen."
We walked through the trees, climbed a low hill of sand and there it was - Yueyaquen, the shining water of Crescent Moon Lake, with a temple built by grateful travellers inside its curve.
For thousands of years, this small, crescent-shaped pond, which amazingly survives in spite of being surrounded by enormous dunes up to 1715m high, has meant salvation to desperate travellers on this desert leg of the Silk Road.
For us, of course, things were not quite so challenging. We had travelled from Jiayuguan, where the final gate in the Great Wall once marked the end of China and civilisation, to the former outpost town of Dunguang, by bus.
Amazingly, for one of the driest parts of the world, it was raining, but we were still able to see through the fogged-up windows the arid wasteland that makes the Gobi Desert such a fearsome place to travel.
Along the way, we spied several crumbling brick towers built by the Ming Dynasty to enable signals warning of enemy invasions to be passed back quickly to the frontier. It was one of these which gave Dunhuang its name, which means "blazing beacon".
Our oasis was the Yang Guan Hotel, where the water mightn't be drinkable but the cold beer certainly was, situated conveniently near to the local market with its array of tasty snack stalls.
Once refreshed, we continued our journey to the end of the road at Mingsha Shan, Singing Sand Mountain, where we abandoned the bus for our camels and a serious desert ride of 2km-3km.
Our two-humped Asian camels took us through huge valleys of sand, up the side of a steep ridge, then along the ridgeline to the base of one of the monster dunes.
There the local people had built a sort of wooden ladder to the top which - as I discovered when I had to retrieve my hat after it blew off - was a great deal easier than trying to climb the sand.
From the top of the ridge, there were spectacular views over the endless waves of sand and the chance to check out the story of how Singing Sand Mountain got that title.
On the way there, Bin, our guide, explained that many years ago a group of soldiers travelling this way had heard the sand singing as they slid down the slope and gave it the name. "If it is summer when the sand is very hot and a big group of people slide down, you can still hear singing from inside."
The price of climbing the ladder up the big dune included the chance to toboggan down in crude wooden sleds which, I thought, might produce a bit of sand singing. Unfortunately not. The sand was damp, our sleds found it hard to get up speed and there was definitely no singing. But, at the bottom, our trusty camels were waiting to take us to Crescent Moon Lake.
Bin also told us that despite being surrounded by these shifting mountains of sand, the lake has never been filled in. About 20 years ago, he said, it was threatened when growing demand for water in Dunguang caused the water table to fall, "but the central government intervened, bought some water to Dunguang from another town, and the lake is now nearly recovered".
It is certainly a remarkable sight to see this perfect crescent moon of water shining amid the sands with the temple behind it surrounded by a few ancient trees.
It's not hard to imagine how miraculous it must have seemed to the hardy traders who came here in their camel trains 1000 years ago.
Getting there: Singapore Airlines operates 12 times a week between Auckland and Singapore and then onward to 62 destinations in 34 countries, including China.
Getting around: World Expeditions operates its Silk Road expedition from Beijing to Samarkand in April, May, August and September. Phone 0800 350 354.
Jim Eagles travelled the Silk Road with help from Singapore Airlines and World Expeditions.