A trip through Gansu province's Dunhuang Grottos is a journey not only back in, but also across time.
Visiting these caves offers an archeological adventure in what could be the set for an Indiana Jones film - replete with hidden passages, secret texts and tales of gold thieves - that provides insight into the cosmopolitan evolution of this ancient Silk Road nexus.
That's because the honeycomb of cavities that pock the cliff in front of the Resonating Sand Mountain in modern Gansu province was whittled over a millennium - meaning the caves were, in the truest sense, shaped by the eras during which they were excavated and renovated.
The chambers became unintended time capsules of Northwest China's historical development from the moment the first chisel was set against the crag's sandstone exterior in AD 366.
According to legend, that was the year monk Yue Zong sat baking in the searing desert sun on a riverbank in front of the mountain, admiring the landscape's exceptional feng shui. As dusk began to ink out the skyline, he decided to dig out a dwelling at the point beneath where the sinking sun touched down on the cliff's crest.
In the solar-heated oven that was Northwest China's ancient desert, a hole in the wall - or a cavern in a rock face - was prime real estate.
The realty's desirability enticed others to copy Yue's idea over the following centuries, and by the 1400s, the crag was whittled into a compound of 735 grottos. For generations, these chambers would be cohabited by a cast of wealthy nobles, monks, artisans, war refugees and stone Buddhist deities.
Their legacies are preserved in the more than 2,000 statues and 45 sq km of murals that have survived until today.
And the 30 caverns that are open to the public reveal a cross section of the millennia that transpired since Yue Zong watched that sunset above the Resonating Sand Mountain.
Cave No 96's 35.5-meter-high stone Buddha, for example, was built in AD 700 during the Tang Dynasty (AD 618-907) but was repainted in the Qing Dynasty (1644-1911). Its face was reconstructed in the Republic period (1911-1949). Its hands were replaced in 1997.
The roof of the seven-story tower built to cover the expanse housing the statue was reconstructed from 1928-1935, and new steps were added between 1963 and 1987.
While the body of the grottos' second-biggest Buddha - a 26-meter-high Tang Dynasty stone sculpture - is entirely original aside from its belt and right hand (scholars call the left "the most beautiful hand in all of China"), the rest of Cave No 130 was adorned during different periods. The murals on the wall were painted during the early and late Tang, and Song (960-1279) dynasties, while the tiling came from the Song and Jin (1115-1234) eras.
Those familiar with Chinese art history - and those hoping to become so - will appreciate the distinctive styles of the different eras evident in the caves' adornments.
The cavern for the 15-meter-long reclining Buddha in No 148, built by the devout Li family in AD 776, was chiseled to have an arch-shaped ceiling resembling the ancient coffins of the time. And the faces on the women figurines found in No 217 float atop double chins, as a portly figure was considered beautiful in the prosperous Tang Dynasty.
No 419 is home to a 1,000-handed Buddha popular during the Sui Dynasty (AD 581-618), when Buddhism flourished in the country, whereas No 275 contains a 3.4-meter-high cross-legged pusu (humbly dressed) Buddha rendered according to the style of the Three Kingdoms (AD 220-280) period when it was carved.
In addition to showcasing the development of dynastic China, the dens that dimple the Resonating Sand Mountain also reveal the histories of the 36 nations that once traveled to, and lived and traded in, this Silk Road commercial hub.
The Western Wei Dynasty (AD 535-556) paintings and Qing-era statues in Cave No 249 show Indians intermingling with local ethnic groups, while Buddha is clad in a Greek robe and stands next to a Hindu god with 13 heads and a snake body.
And the Sui Dynasty Buddhas in No 292 are clad in ancient Persian attire colored with Afghan pigments - worth more than gold at that time. Gold, too, was used in this cavern's artwork but was long ago stripped away by burglars.
But the real hidden gem taken from the grottos' treasure trove was the secret library of Cave No 17.
Foreigners raided the collection of more than 40,000 writings and artworks, which span several centuries and languages, in 1900 - the year the collection was discovered behind a secret door built into the cavern wall about nine centuries earlier. About 10,000 of the artifacts are still in China, while most of the rest are in Japan, Russia and the United States.
To this day, nobody knows why monk Hong Bian - whose ashes are mixed into a statue of his likeness in the cave - stashed these masterpieces in the hidden compartment around AD 1035. Most experts theorize it was to protect the ephemera from the impending Xixia King's invasion. If that's the case, it worked, but Hong likely had little inkling foreigners would eventually seize the works almost a millennium later.
But even with the library gone, the wealth of historical riches found in the Dunhuang Grottos make them an archeological Aladdin's cave (the story is actually set in an unnamed Chinese desert city rather than the Middle East).
So visitors to these cliff-side caverns can discover Northwest China's past and present shaped both by, and in, the sands of time.
Sliver of shimmering silver in stark, sulfur sands
Water has for thousands of years directed the currents of development in Gansu province's Dunhuang city - the only desert oasis for hundreds of kilometers in any direction as the camel trots.
The Crescent Moon Lake looks like a mirage in the desert. Cao Zhizheng / Asia News Photo The centerpiece of the city's water table is Crescent Moon Lake, a bowed aquatic sliver shimmering in the cracks of several tumbling dunes.
This water sickle's edges are fleeced by greenery, beyond which the stark yellow sands of the Gobi desert mash together in dunes that roll for about 200 km to the south. Surely, the island of lushness seems so surreally out of place in the otherwise barren wastelands that it appears as if it were a mirage.
The topography of this parched landscape is shaped like the backs of the camels that plod across its slopes. Visitors can explore the swooping sand drifts while seated between these creatures' joggling humps.
And it's this very topography that has protected the lake from being swallowed by the area's frequent sandstorms. The roaring winds - from which the Resonating Sand Mountain (Mingshashan) takes its name - always blow east to west and from peak to peak across the dunes. This sends an aerosol of sand flying over, rather than into, the water.
But while the Crescent Moon Lake isn't in danger of being filled in from above, it is being sucked out from underneath. Dunhuang's groundwater - fed by about 20 minutes of rain a year - has become an even scarcer resource as the city's thirst for development continues to rapidly sponge it up. Over the past several decades, this has caused the pool to shrink into a puddle of its former self.
However, the Crescent Moon Lake's waning may be averted by ongoing city government campaigns to cap Dunhuang's population at 800,000 in the greater area, and to prohibit the drilling of new wells and cultivation of new land.
Despite its small size, the lake remains a big attraction for visitors.
Unlike the Silk Road-era travelers who came to the watering hole to quench their physical thirst, contemporary tourists come to drink in the scenery.
But liquid refreshment is still available - this oasis has its own drink stand, a pagoda proffering boiled apricot juice, a local specialty favored by locals for its hydrating qualities.
And visitors will not want to be parched while slogging up the dunes rising from the lake. It's a tough climb to the top, as every step buries climbers' legs up to their shins in sand. Vendors near the base rent out neon-orange, knee-high cloth booties that - in addition to making a fashion statement, of some kind - keep the desert out of wearers' shoes.
But while the distances up and down the sand piles are equal, the return trip is made much faster by "sand sledding". Visitors can hop aboard a bamboo toboggan and whoosh down the declivity, spraying rooster tails of dust behind them.
Whether by sled, foot or camelback - or by all three - exploring this oasis is a must for any traveler to Dunhuang.
As a fountainhead of scenic beauty and historical culture, Crescent Moon Lake shines bright as a star attraction for visitors to Gansu's otherwise desolate deserts.
Everyone's invited to this Silk Road costume party
Gansu province's Dunhuang is hoping to restore its glory days by reconstructing its ancient city - and will do so by following the dynastic-era blueprints from the secret library a mysterious monk hid in a cave in 1035, the local government says.
Dunhuang's biggest project in modern times is intended to "create a role-playing holiday for contemporary people", the CEO of J.A.O. Design International Architects Ltd, James Jao, says.
"We're looking to create a theme park that is also a way of living," he says.
"It's not difficult to recreate the ancient structures. The trickier part is recreating a lifestyle - to build a place where you walk through the gate and into the Han Dynasty (206 BC-AD 220)."
To this end, planners are considering having visitors exchange their modern money for ancient coins and swap their contemporary clothing for Han-era attire upon entering the city.
Jao says he took inspiration for the concept from the modern US tradition of the toga party, in which revelers dress in ancient Roman robes.
"I want to have a Chinese toga party, and everyone's invited," Jao says.
The project will cover one-seventh of the 7-sq-km city of 5,000 residents. It will cost 3 billion yuan ($451 million) and take five years to complete, Dunhuang's planning commissioner Qi Xingji says.
"We're trying to create the right mix of modern facilities and ancient lifestyles," Jao says.
The idea is to show 1,000 years in three days, he says.
To figure out how best to do that, J.A.O. Design distributed more than 500 surveys to locals and visitors.
The hope, the city's Party Chairman Sun Yulong says, is to create stronger staying power for tours to the Dunhuang Grottos, Crescent Moon Lake and the westernmost terminus of the Han Great Wall. Visits currently last for an average of two days.
"It will make a huge difference to the prosperity of our city if we can get people to stay another day or two," Sun says.
"And this ancient city reconstruction project is our best option for making this happen."
Tourism is Dunhuang's No 1 industry, accounting for about 30 percent of the local economy, government figures show.
The rebuilding project's design is based on the ancient urban planning documents discovered in 1900 in the secret library of Hong Bian. For reasons still unknown, the monk stashed the records, behind a fake wall in the Dunhuang Grottos' Cave No 17, almost 1,000 years ago.
The reconstructed city will contain six zones, Qi says. There will be a Buddhist monastery area; a museum and international exhibition area; a hotel, guesthouse and service area; a commercial and trade area; a performance area dedicated to local traditions; and a central district industry park.
Sun says he hopes the new attraction would lure not only domestic but also foreign tourists.
"Dunhuang is the central meeting point of China and Central Asia," Jao says.
"We're trying to recreate the 36 lifestyles of the 36 nations that once converged here. This historical fusion of cultures must be recreated."
During the Han and Tang (AD 618-907) dynasties, the city was the only oasis in the desert swath between Central Asia and the ancient capital Xi'an (then called Chang'an). The Silk Road nexus also hosted the largest proportion of foreign residents in China.
"If China wants to influence the world again, the cultures have to meet," Jao says.
"And there's no better place for this than Dunhuang."