When the firstgrotto was dugout in 366， theDunhuang areawas blanketed with green forestsand fields. In the Tang Dynasty（618-907）， the desertificationprocess intensified in the area，leaving Dunhuang coveredwith dried riverbeds andendless stretches of shiftingsands. For hundreds of yearssince the mid-16th century， theunattended Mogao Grottoessuffered from natural disastersand man-made damage. In1944， the National DunhuangArt Research Institute， thepredecessor of the DunhuangAcademy， was established toconduct the protection andrestoration of the MogaoGrottoes alongside the study ofDunhuang culture.

Restoring the Old

The murals are one of theprimary targets of cultural relicsprotection in Dunhuang. Thewalls were continuously paintedfrom the Sixteen Kingdomsperiod （304-439） to the YuanDynasty （1271-1368） and arenow facing various maladiesafter centuries of weathering.

A large one among theMogao Grottoes in Dunhuang，Cave 55 was constructedaround the year 962 duringthe Northern Song Dynasty（960-1127）. According to YinZhihong， a mural restorationexpert from the DunhuangAcademy， since protectionwork first began on this cave’smurals in 2022， everythinghas strictly adhered toseveral procedures： First， acomprehensive assessment of itshistorical， artistic， and scientificvalue is conducted， followedby a thorough investigationand documentation of thecurrent state of the murals andmonitoring of the environment.Then， a scientific analysis ofthe materials used in the muralsand the mechanisms for theirdeterioration is performed.Conclusions from the analysisguide the selection of materialsand techniques for restoration，and a plan for conservation andrestoration is then developedand implemented. Yin stressedthe importance of this set of procedures for cultural relicspreservation.

“The Mogao Grottoescurrently hold 45，000 squaremeters of murals，” saidYin. “Modern cultural relicconservation adheres tothe principle of minimalintervention. The materialsand techniques used inthe conservation andrestoration of Cave55 are all reversible，aiming to restorethe old to itsprevious statewhile avoiding‘protective’damage. Ifthe besttechnology available doesn’t fit，we’d rather keep it as it is to leavespace for future restoration.”

“Many problems have alreadybeen fixed， and the currentproblem being treated is peeling，”said Yin. Peeling is a commonproblem for murals， when thebase color layer or pigment layerof murals begins cracking， curlsup， and even falls off. Even themost skilled professionals canonly repair an area the size of apalm in a day. According to Yin，restoration of the 500 squaremeters of murals in Cave 55might take a team of seven oreight professionals four to fiveyears.

“The cultural relics we haverepaired can be preserved forat least another 10 years， oreven several decades，” he said.“We want to make sure futuregenerations can still appreciatetheir beauty.” The DunhuangAcademy boasts over 100 muralpainters and repairers like YinZhihong. For the past 80 years，the institution has developeda complete set of muralconservation techniquesand scientific processes，allowing Dunhuangculture to thrivecontinuously.

New Digital Life

Achieving permanentpreservation and sustainableuse of cultural relics hasalways been an elusive goalfor conservation experts. Inthe late 1980s， Fan Jinshi，then executive deputy directorof the Dunhuang Academy，first proposed the concept of“Digital Dunhuang.” In April2006， the Dunhuang Academyfinally established a digitalcenter， which was later renamedthe Institute for the Digitizationof Cultural Heritage. Theinstitute primarily appliesdigital technology to effortsrelated to the Mogao Grottoesand relevant cultural relics，giving new life to Dunhuangcultural heritage in the digitalworld.

The Dunhuang Academy hasnow developed a complete setof key technologies and workingstandards for digitizing murals.“This high-fidelity automaticmural photography equipmentis guided by software to takesegmented shots according toset parameters and sequencingto capture all information of theimages on the walls.”

In Cave 341 of the MogaoGrottoes， Yu Yin， a staffmember with the Institute forthe Digitization of CulturalHeritage， was checking imagestransmitted in real time. “Byenlarging a picture， you canclearly see every detail，” he said.“For instance， you might noticewhen a painter drew the fingersof a figure too thick or the toeswere off. It’s amazing.”

After data collection， manualpiecing of photos is performed.Because each person can onlypiece together about 20 photos aday， completing the entire muralon each wall will take about twomonths. The puzzle must bepieced together perfectly; eventhe hair on figures must achieve“seamless connection.” Threedimensionalreconstructionof painted sculptures requiresmassive amounts of data. Justfor the main Buddha statue inCave 45 of the Mogao Grottoes，which is over one meter high，digital reconstruction used morethan four million triangularmeshes. The body length ofthe Nirvana statue in Cave158 is 15.6 meters， and threedimensionalreconstruction ofthis cave took two years， withtriangular meshes numberingover 100 million.

At the Institute of Fine Artsunder the Dunhuang Academy，artists have been recreating thegrand Tang Dynasty ambianceof Cave 172 of the MogaoGrottoes. This cave was builtduring the heydays of the TangDynasty. Each of the northernand southern walls featuresa giant mural， representativeworks of the mural art of theprosperous Tang Empire.However， many of the muralsare now discolored and blurred，and some parts are evenmissing. In 2016， a dozen artistsfrom the Institute of Fine Artsstarted working together torestore and replicate the muralsof the entire cave. It is the firstcomplete-cave mural replicationproject by the DunhuangAcademy.

Copying is a key measure forpreventive conservation of themurals in the Mogao Grottoes.“The hardest part in restoringand replicating Cave 172 is someof the mural colors have turnedblack，” said Han Weimeng，deputy director of the Instituteof Fine Arts， who is overseeingthe project. “Restoration andcopying involve research anda process of conversing withthe ancient people. Based onthe accurate forms of figures，we are decoding the colors andreading historical documentsto ensure the essence， energy，and spirit of the original muralsare eventually presented in thecopied works.”

Today， “Digital Dunhuang”has become an importantwindow and brand forpromoting Dunhuang cultureto the world. On August 27，2024， the Dunhuang studiesresearch library， an onlinedatabase gathering the researchachievements and firsthandmaterials on Dunhuang studiesfrom around the world， wasofficially launched， providingan open and shared academicresource platform for scholarsglobally.

Dunhuang culture originatesfrom China， but Dunhuangstudies belong to the world.