Going through the pages of two beautifully-bounded albums featuring the Yungang Grottoes near Datong, in north China's Shanxi Province, which were published in 1991 and 1994, readers cannot help but gasp in amazement at the glories of early Buddhist art in ancient China.

The albums were published well before the Yungang Grottoes were listed as a world cultural heritage site by the United Nations Educational, Scientific and Cultural Organization (UNESCO) in 2001.

Li Zhiguo, the veteran Yungang grottoes scholar who painstakingly worked out the chronology of the grottoes, knows only too well how much more work and study lies ahead for grotto staff in their effort to preserve the ancient Buddhist legacy.

According to his research, as a result of the declining power of the Northern Wei Dynasty (AD 386-534), the massive construction and sculpting frenzy gradually came to an end between the years 520 and 525.

During the early Tang Dynasty (AD 618-907), some Buddhist believers and a Tang monk named Yanchan tried to make some repairs.

Between 672 and 1049, the Yungang Grottoes were almost totally neglected by the writers of local annals.

Over the next 600 years, the grottoes suffered damage in a number of wars and also underwent repair and reconstruction.

The most prestigious guest of honor at the grottoes after their hundreds of years of prosperity and decline was none other than Emperor Kangxi of the Qing Dynasty (1644-1911), who visited the site in 1696.

Somehow, the grottoes were "rediscovered" by a Japanese scholar, whose writing aroused international and especially Japanese interest in the grottoes. Between 1939 and 1944, the Japanese undertook excavation and survey work eight times, carting away some of the site's most valuable relics.

"At Japan's National Museum of Art in Osaka, I saw a lot of Buddha heads taken from Yungang," Li said in a television interview. Similar looting occurred at Tianlongshan, in Taiyuan, the capital of Shanxi Province, and at Maijishan in Northwest China's Gansu Province.

"I was so upset when I saw a large head of the Buddha there that I told the chief curator that the head had been separated from his body," Li said. "I also asked him when the head could return home to rest in its rightful place?"

Proper protection of Yungang was not possible before the founding of the People's Republic of China in 1949.

In 1961, China listed the caves in its first group of historical sites under State protection.

Li Zhiguo took on his job as curator of the site in 1962.

In the earlier years, there was not even a bus between Datong and the grottoes. He had to walk 16 kilometers from Datong to Yungang, and it usually took about two hours each way. So he often spent the night in a small house in the village nearby.

In his eyes, the early Buddhist statues possess a special intimacy and allure, and this has kept him there for 40 years.

During the "cultural revolution" (1966-76), the grottoes escaped looting, as Li and his colleagues managed to close up the caves before the Red Guards arrived.

Serious protection work started in 1973, after the late Premier Zhou Enlai (1898-1976) accompanied then French President Georges Pompidou (1911-74) on a visit to the grottoes.

Li Zhiguo pointed out to the premier that erosion was seriously damaging the ancient art works and that the local surroundings detracted from the grandeur of the ancient historical site.

In 1985, Yungang was listed as one of the first group of sites China presented to UNESCO for consideration for listing as a World Heritage site.

However, at that time, the grottoes were suffering from serious pollution, as they were surrounded by about 30 coal mines. A State-highway passed only about 350 meters from the grottoes, and heavy-duty trucks carrying coal lumbered up and down the highway day and night.

The caves and many statues were covered with soot and were being further eroded by acid rain.

Starting in 1987, under the guidance of Su Bai, a well-known professor of archaeology from Peking University, Li and his colleagues undertook the work of re-surveying and cataloguing the more than 252 caves and 51,000 statues at the site.

It took them years to complete the work. The two albums mentioned above are part of the fruit of their hard work.

In 1998, the central government invested 230 million yuan (US$27.7 million) to reroute the State-highway, moving it away from the grottoes. Many of the small coal mines were also closed down.

Li Xueqin, who started work at the grottoes as a guide in the late 1970s, still recalls the days when she and her colleagues tried to remove the soot from the statues.

"We worked with small brushes," she said in an interview with the Hong Kong's Phoenix Television. "We had to be very careful. If we brushed even a little bit too hard, we could damage the surface."

All their hard work helped Yungang when it came time to make its case with UNESCO.

In 2001, Yungang Grottoes was finally listed as a World Cultural Heritage Site by the world organization.

In the UNESCO committee session deliberating on Yungang Grottoes' qualifications for World Heritage listing, the committee declared that Yungang constitutes "a classical masterpiece of the first high phase in the development of Chinese Buddhist art."

According to a UNESCO report, the factors justifying listing Yungang as a World Heritage Site include:

The assemblage of statuary of the Yungang Grottoes is an unparalleled example of early Chinese Buddhist cave art.

Yungang cave art represents the successful fusion of Buddhist religious symbolic art from South and Central Asia with Chinese cultural traditions, starting in the 5th century AD under imperial auspices.

The power and endurance of Buddhist belief in China are vividly illustrated by the Yungang Grottoes.

The Buddhist tradition of religious cave art had its first major impact at Yungang, where it developed its own distinct character and artistic power.

Since the listing an endless string of scholars, artists and architects have swarmed onto Wuzhou Mountain.

Many works have pointed out that Yungang is a living testament to Chinese people's ability to assimilate foreign cultures and the cultures of ethnic minorities. Apart from Buddha carvings, researchers also found valuable resources for the study of ancient Chinese music and dance art.

Right now, many researchers are still concerned about environmental pollution from nearby city of Datong.

Researcher Huang Jizhong of the Yungang Grottoes Study Center recently pointed out that two big low-grade coal mines only a kilometer from the grottoes are a major threat.

Both mines produce coal with a high sulphur content that could quite possibly be contributing to the acid rain in the area. At the same time, people living near the heritage site use a lot of coal for cooking and local industries, and the emissions also affect the air quality around the grottoes.

Huang warns that the powdering of the surface of Buddhist carvings is becoming increasingly serious, and that effective measures to stop it must be taken immediately.

(China Daily June 22, 2004)