Roaring engines rudely interrupted the tranquility of Ayong Village on a fine day in December 2004.

The driver of an excavator was trying to lift a 5-ton boulder and put it on a truck. But it was obviously too big. Finally, the driver managed to raise the boulder and let it crash onto a smaller one.

Although the huge rock cracked in two, it remained difficult for the workers to load and carry it away.

The boulder was just one of many that archaeologists had to remove before they could excavate six ancient tombs to be affected by the Xichang-Panzhihua Highway under construction in this village in Dechang County of Liangshan Yi Autonomous Prefecture in Southwest China's Sichuan Province.

If it proved so difficult to remove such boulders with modern machinery, how did the builders of the tombs manage over 2,000 years ago? Where did the boulders come from? Did the tombs really belong to the little-known Qiong people?

These are just a few of the many myths that continue to puzzle experts from Sichuan Provincial Archaeology Institute, Liangshan Prefecture Museum and Xichang Cultural Relic Administration who excavated the tombs.

"There are no similar boulders nearby, and it would have been almost impossible for ancient people to carry them up to the tombs from the Anning River," said Liu Hong, curator of Liangshan Prefecture Museum, who has years of experience in dealing with such tombs.

"We are still looking for the origin of these boulders, so we can estimate the production capacity of the time and the number of people who took part in their construction."

Cultural channel

Liu's introduction to the Boulder Tombs provided more clues to the country's experts trying to piece together the history of the Hengduan Mountains that lie on the border of Sichuan and Yunnan provinces and the Tibet Autonomous Region.

Over 60 experts from across the country discussed the importance of the Hengduan Mountains, also known as the Tibet-Yi Corridor, at a seminar held last month in Xichang, seat of the Liangshan prefecture government.

The concept of Tibet-Yi Corridor was first raised in 1980 by renowned Chinese sociologist Fei Xiaotong (1910-2005).

"We can outline a corridor from north to south with the centre at Kangding (a county in Sichuan). This corridor, which lies right between the Yi and the Tibetan people, has rich deposits of historical remains. This ought to be a precious source of history and linguistic sciences," Fei wrote in the first issue of Social Sciences in China.

Besides Sichuan, Yunnan and Tibet, the Tibet-Yi Corridor also spans Gansu and Qinghai provinces to the north.

The area's huge mountain range about 1,200 kilometers long and 750 kilometers wide is crossed from north to south by six rivers Nujiang (Salween in Myanmar), Lancang (Mekong in Southeast Asia) and Jinsha, Yalong, Dadu and Minjiang, four tributaries of the Yangtze River.

Professor Duan Yu, director of the Bashu Culture Centre in Sichuan Normal University, said that Liangshan was a transportation hub for people in ancient times, moving along the deep valleys between the northwestern plateaus of China to Southeast Asia.

"Archaeologically speaking, Liangshan is a complex region," Duan said. "Ancient tribes in Liangshan had developed individual cultures before they were converged into bigger cultures."

He pointed out that cultural relics found in Liangshan have several origins, notably the Bashu culture in the Chengdu Plain and the grassland culture of northern China. Their clash with the local culture resulted in great diversity.

Apart from the Tibetan and Yi minorities, Qiang, Nu, Pumi, Dulong, Lhoba, Monba, Hani, Naxi and dozens of other ethnic groups have been living in this region for centuries. Due to a lack of contact with the outside world, most of these ethnic groups have retained strong identities.

Among more than 4 million people in Liangshan, 1.8 million, or nearly 45 per cent, are Yi people. According to Li Xingxing, research fellow with the Sichuan Ethnology Research Institute, the Yi's ancestors arrived in Liangshan from Yunnan's Zhaotong via the Jinsha River, establishing a unique paternal clan society.

Without forming any political system in Liangshan, they ruled themselves with the clan system. Each clan, or jiazhi, had its own woods, pastures and hills. Members of a clan were required to support each other and join in battles against other clans. An assembly of chieftains decided all matters.

An interesting tradition of the Yi people was that the name of the son contained the last words of his father's name for example the son of Apu Jumu was Jumu Denglun. This enabled the Yi to distinguish clan members and carry on the lineage.

Little-known history

But researchers still know very little about the history of this area, Professor Sun Hua, vice-director of Peking University's School of Archaeology and Museology, told a meeting of local archaeologists in 2004.

Sun and his colleagues have started researching the bronze ware in the Eastern Yunnan Plateau. Liangshan, which borders Yunnan, is an important part of this area.

Sun said that Sima Qian of the Western Han Dynasty (206 BC - AD 24) recorded that Dian, Yelang and Qiongdu were three major agricultural regions outside the Bashu region in Southwest China.

Some work has been done about Dian and Yelong and little about Qiongdu, because researchers haven't pinpointed the location of any of the three regions.

The Boulder Tombs discovered in the past few decades in Xichang could be related to the Qiong people, Sun said, but more studies are needed to make breakthroughs in this field.

"Liangshan is archaeologically important as it is the origin of many rivers in eastern Yunnan and links surrounding regions," Sun said. "Studies of this region will not only enrich local history, but also help us understand the culture and the minorities of Southwest China."

Li Xingxing said that Liangshan is gifted with a very special geological location, making it a centre of ancient cultures.

The banks along the Anning River, a smaller tributary of the Yangtze which flows across Liangshan, have been inhabited by Qiong people since ancient times, Li said.

The Anning River valley, a flatland of 1,800 square kilometers, is the second-largest plain in Sichuan. Many historical annals record that its early inhabitants were farmers.

More than 200 Boulder Tombs have been found in Dechang County and other parts of Xichang. The oblate boulders were placed in front of or at the back of the tombs. They were also used to cover or make walls for the tombs.

Small pebbles were placed at the feet of the boulders to keep them erect. But it's hard to imagine how the huge boulders were lifted to cover the tombs, said Liu Hong.

Only a few bronze and iron knives and arrowheads were found, indicating the scarcity of metal when the tombs were constructed.

Liu said they found a slope laid with pebbles and pottery shards between two tombs. But it's still too early to determine how the boulders were dragged up such slopes.

"Since we found this slope, we are one step closer to unraveling the myths," Liu said, adding that more evidence has been found to prove that the tombs were built by early inhabitants of the region.

(China Daily July 11, 2006)