DUNHUANG, China - Deep in China's Gobi desert 1,700 years ago, Buddhist monks carved small caves into the sides of cliffs. The caves were beautifully painted to illustrate Buddhist stories and used to store important religious documents.

Over the centuries the caves have survived many dangers: earthquakes, floods, and foreign explorers who took souvenirs. Russian soldiers even sheltered in the caves during a war in the 1920s. They filled them with smoke from their cooking fires.

Today the caves are facing a new danger: tourists.

The site of the caves is called Mogao Grottoes. In 1979, the first year the caves were open to the public, they received 26,000 visitors. This year, up to 1 million people may visit them.

Protecting The Mogao Grottoes

Visiting tourists can damage the caves with their large, bulky backpacks and hot, humid breath.

Chinese and American experts have been working together for 25 years to protect the caves. The Dunhuang Academy here partnered with the Getty Conservation Institute of Los Angeles to make a long-term plan to protect the treasures of the Mogao Grottoes.

The two teamed up because the researchers at the Getty Institute got a lot of experience working on important sites over the years, including the Tomb of Queen Nefertari and the Great Sphinx in Egypt. The Getty was founded in 1985. The Mogao Grottoes is the group's longest-running project.

An important research question is how many visitors the caves can handle in one day. Initially, Getty scientists decided only 3,000 visitors a day were possible. But there was a lot of interest from tourists and today, about 6,000 people see the caves each day. Tourists must have reservations, and they can only visit certain caves.

The two groups also hope they can introduce the caves to an international audience. Most of the tourists that visit the site today live in China.

"Some Of The Best Work"

A $50 million visitor center opened this month. It was designed by Beijing architect Cui Kai, who shaped the building like the nearby sand dunes.

At the visitor center, tourists can watch two films about the caves. The films will help visitors understand the caves and paintings better. They will also help to protect the caves by allowing tourists to spend less time inside them.

When researchers work at sites around the world, it's called working "in the field." According to Tim Whalen, director of the Getty Institute, the work in China is "some of the best work we've ever done in the field."

The Getty's scientists are conservationists. They are trying to conserve, or protect, the caves. The first step is to do a survey. They closely examine the caves, trying to learn everything about them. Next, they figure out what dangers the caves face, like blowing sand and hot, humid air.

A Cave Expert's View

Neville Agnew is the Getty's top expert on the caves. He has been visiting Dunhuang since the 1980s. He has visited more than 50 times overall.

Agnew has seen the area around the caves change a lot. When he first started coming here, the caves were very isolated - there was nothing else around. There wasn't even a modern airport in the area. At that time, China was much poorer than it is now.

Thanks to an economic boom, many Chinese people are much richer than they were in the 80s. More people have the money to visit places like the Mogao Grottoes.

Agnew thinks more and more people will be visiting the caves.

It doesn't take a lot of imagination to predict what might happen in the future, Agnew said.

What Life Was Like Long Ago

There are many reasons scientists are working to save the cave paintings. The paintings are an important collection of Buddhist art. But they also are important for historical reasons. They show what life was like long ago in China.

By studying the paintings, researchers have learned about very old Chinese clothing, dance, musical instruments, sports, and even a sport known as "elephant lifting." The caves also contain many religious sculptures, including a huge carved Buddha dressed in orange robes. The Buddha is more than 100 feet high and almost 40 feet wide.

The conservationists hope that their plans for the cave will keep the paintings and sculptures in good condition for the future.

"Ideally, these methods can be adapted at other sites, both in China and elsewhere in the world," said Wang Xudong of the Dunhuang Academy.