By Li Yanan, Dong Yingxue, People’s Daily
Within the Kizil Thousand-Buddha Caves in Baicheng county, Aksu prefecture of Xinjiang Uygur autonomous region, visitors are greeted by a refreshing coolness – a welcome respite from the arid expanse of northwest China. Here, among the country’s earliest large-scale grotto groups, cave walls shimmer with rows of jewel-toned diamond patterns. Each geometric frame encapsulates a story, with blues and greens from millennia-old murals unfolding in solemn procession across stone canvases.
Yet time has been unkind. As China‘s oldest surviving Buddhist cave complex, Kizil confronts relentless preservation challenges. Centuries of aging, smoke damage, and human intervention have compromised its artistic legacy. “Restoration is painstaking,” said Yang Jie, a staff member at the Kizil Grottoes research institute. “A single four-to-five-square-meter mural can demand over two months of meticulous work.”
Of Kizil’s 349 caves, 107 contain murals spanning nearly 4,000 square meters, only a fraction of their original glory. In the early 20th century, foreign expeditions removed significant portions. According to Zhao Li, a researcher at the institute, around 500 square meters of murals from 59 caves were stripped away.
From 2002 to 2016, Zhao collected 487 high-resolution images of these scattered fragments from over 20 international museums and brought them back to China for digital restoration. This meticulous effort required extensive research to determine each mural’s original location. She digitally cropped and reassembled the pieces like a massive jigsaw puzzle, culminating in 2020 with the most comprehensive catalog of displaced Kizil artworks – a 1,200-plate compendium mapping each artwork to their ancestral caves.
Where soot obscures murals, advanced technologies now illuminate. A project jointly launched by the China Cultural Heritage Information and Consulting Center, the Digital Culture Laboratory under Tencent’s Sustainable Social Value organization, and the Tencent Research Institute, is pioneering the use of terahertz imaging, X-ray analysis, and large language models to identify, reconstruct and digitally restore damaged artworks
In Cave 161, layers of grime cloak artistic narratives. A research team from the School of Art and Archaeology of Zhejiang University employed terahertz time-domain spectroscopy to non-invasively penetrate the darkened surfaces, revealing pigment layers beneath and effectively seeing through centuries of residue without damaging the murals.
“We’ve identified one figure, two concentric circles on the dome, and diamond motifs, all classic Kuqa artistry,” said Zhang Hui, professor with Zhejiang University, gesturing toward the blackened ceiling. Next, the team will digitally reconstruct these findings using advanced analytical techniques.
Meanwhile, Cave 38’s fragmentary murals defy conventional restoration. Here, artificial intelligence offers a breakthrough: The Digital Xinjiang Group utilizes image recognition to hypothesize and reconstruct missing sections – a technological leap accelerating preservation.
At the foot of the Mingwutag Mountain, poplars planted decades ago by researchers stand sentinel beside the caves. Today, as these silent witnesses guard Xinjiang’s cultural legacy, technological innovation breathes new vitalityinto ancient pigments, ensuring their stories endure for generations.
