In popular culture, there is an unusual expression: "nine-story tower haunted by ghosts." And an online novel that spawned a raft of screen thrillers on the theme of this "haunted tower" on the Qinghai-Tibetan Plateau has grabbed people's imagination in recent years.

It is perhaps hard to tell whether it is a spotlight or a gloomy shadow that has been cast over the Reshui graveyard, an archaeological site of around 300 tombs dating back to between the 6th and 8th centuries, in Dulan county, Qinghai province.

Having gained fame in recent years, continuous robberies have led to many treasures being taken from the burial site. However, in March, 2018, a nationwide legal-enforcement campaign was set up to combat tomb-raiding and retrieve lost artifacts to put an end to that chaos.

To rescue this ransacked site, archaeologists began an excavation of a major tomb at the graveyard－Xuewei No 1－in September.

Since then, the fruitful discoveries made there have helped to lift the veil of mystery surrounding the site, adding more pieces to the jigsaw that make up the ancient Silk Road.

"It is so far the most complete ancient tomb ever excavated on the Qinghai-Tibetan Plateau," Han Jianhua, the lead archaeologist on Reshui graveyard, told the media at a briefing in Beijing on Nov 22 at a conference of the National Cultural Heritage Administration. "The entire structure of the grave has been cleared out, which is a breakthrough for our studies into funereal customs in the region."

The outer wall of the newly-excavated tomb spans 33 meters from east to west and 31 meters from north to south, and is built up by thick layers of earth. Remains of cloisters and sites for religious sacrifices were also unearthed.

And Han was quick to emphasize that the abundance of findings in terms of cultural relics offered evidence of its crucial role in cross-cultural exchanges at that time.

The kaleidoscopic array of artifacts ranging from wooden slips bearing Tibetan words, gold ware and silk pieces, to lacquer ware, turquoise, and crystal, were uncovered there. And some of the decorative patterns on these items feature the styles typical to the Sogdian and Sassanian people－both originally from today's Iran and Central Asia.

"The complex structure of the graveyard and the myriad funeral objects and diverse range of styles reveal a slice of history that shows how the different ethnic groups communicated with each other," says Zhu Yanshi, a researcher with the Institute of Archaeology at the Chinese Academy of Social Sciences.

"The term 'nine-story tower haunted by ghosts' is a bit of a gimmick, and a little misleading," he adds. "Additional scientific research will present a more rounded picture and give the public a better understanding of its significance."

In addition to the findings at Xuewei No 1 tomb, new archaeology discoveries in Northwest China have uncovered historical texts related to the Silk Road from the Tang Dynasty (618-907) to modern times, the pinnacle of cultural and economic prosperity in the history of dynastic China.

As a crossroad of cultures at that time, the region witnessed the rise and fall of the Tang era and the Tibetan Tubo Kingdom (618-842), as well as several other regimes established by different ethnic groups that were closely interconnected.

For example, on the eastern edge of the Qinghai-Tibetan Plateau, archaeological discoveries made in September in Tianzhu Tibetan autonomous county, Gansu province, unveiled more evidence of the Tuyuhun khanate－a crucial power that was a contemporary of the Tang Dynasty. An unearthed tomb of a Tuyuhun ruler, rare for its kind, contributed to filling in some of the gaps in the family tree of the rulers from that lost khanate and its key role on the Silk Road.

Secret crown

Another discovery in Qinghai province raised scholars' eyebrows at the conference of the National Cultural Heritage Administration on Nov 22.

On a mountain slope in the province's Ulan county, over the course of a yearlong excavation, starting in September 2018, archaeologists unearthed a tomb of a Tubo noble with exquisite murals.

"Tombs decorated with murals were common at that time in the area inhabited by Han people," Tong Tao, chief archaeologist working on the site, says. "But it's extremely rare among Tibetans."

The murals contain scenes of hunting and banquets, animals and flowers, as well as other auspicious patterns.

"The drawing technique is Tang style, but what is depicted in the murals is the nomadic life on Qinghai-Tibetan Plateau," Tong says.

Discovery of a concealed compartment in the tomb brought an even bigger surprise, because no such thing had ever been found in any ancient grave in China, according to Tong, let alone the fact that a gold-gilt crown with pearls and sapphires, sitting alongside a gold cup inlaid with turquoise, was found inside.

"Such things only existed in novels or films before, not in real archaeology," he smiles. "Crowns easily attracted tomb raiders, so it is rare to find such an artifact during archaeological research in China. We can figure out how scrupulous the designers of this grave were to ensure its safety."

As the crown is decorated with winged-dragons and phoenixes, and the concealed compartment is put on some grain seeds, often indicating expectation for a country's prosperity, Tong speculates that it represents the tomb occupant's close link with the Tubo rulers.

"After over one millennium, the crown still stands there and a cup is put in front of it," he says. "It indicates worship toward a time of glory and legend."

He also adds that it represents the peak of Tubo culture, when it had gathered wealth holding the doorway of the Silk Road and a highly developed civilization was incubated as a result.

Ruins of a fortress

More discoveries have been made further westward along the Silk Road. In Yuli county, Xinjiang Uygur autonomous region, an excavation of a Tang Dynasty beacon tower has been full of new findings, even though it only started in October.

Over 800 artifacts have been unearthed from the site named Keyak Khduk, including precious documents written on paper and wood slips, according to Hu Xinjun, a leading archaeologist on the program. Military logs, personal letters, account books, and works of literature, combine to portray not only how frontier military units of the Tang Dynasty were organized and managed, but also what the soldiers' lives were like while safeguarding the outpost.

It has been over a century since Marc Aurel Stein, a British explorer, did preliminary research on the site in 1914.

"These newly found documents are encyclopedic, and fill many gaps in our research," Hu says. "Through the letters, we have a full understanding of the military network then, as the names of many outposts have disappeared in historical recordings."

There are 11 remnant beacon towers in Yuli county, unveiling the history of Anxi Frontier Command, established by Tang in 640 to rule the "west regions" in today's Xinjiang.

"There is also evidence to prove the rule of Chinese central government over this area in history," Hu says.

Speaking of these new findings in Northwest China, Song Xinchao, deputy director of the National Cultural Heritage Administration, says they join to "compose a chain of stories" on the Silk Road.

"The relations between different ethnic groups and between central government and frontier regions are thus vividly portrayed," he says. "In-depth communication is seen at these sites. That has always been the fundamental strength to maintain national unity with diversity and prosperity."