Some of the world's most intriguing sites have still somehow managed to escape the scrutiny of the guidebooks.

An example is Sanxingdui, a mind-boggling museum of bronze artefacts unearthed in China's Sichuan province between 1986 and 2001.

These remarkable figures look as though they could have come from Mayan sources, or directly out of Star Wars. Their origin is as yet a total mystery; even more mysterious is why Sanxingdui, just an hour by road from Chengdu (the caal of China's Sichuan province) is not more widely known.

These are no mere artefacts, but a stunning, mind-boggling expo of statues that could have been sculpted by a 4,000-year-old Salvador Dali.

Xie Wei Fan and Ling Shu Yun, a young couple from Guangdong, are visitors to Sanxingdui Museum.

"I've never seen anything like these statues, except maybe in Canada," says Wei Fan. "They remind me of American Indian sculptures."

The Sanxingdui story began nearly 5,000 years ago - but its modern version started in 1929, near the city of Guanghan, some 50km NE of Chengdu. To the north of Guanghan's Yanjiang or Yazi ('Duck') River is a highland known as Yueliangwan ('Moon Bay') and across the river three mysterious earthen mounds rise prominently above the plains; hence the name Sanxingdui (meaning 'three star mounds')

In the spring of 1929, a Yuelingwan farmer discovered a large cache of buried jade, which was later investigated by archaeologists from the Huaxi University Museum. As well as jade, the archaeological team uncovered large quantities of strikingly crafted pottery. But because of wars and the Cultural Revolution, Yueliangwan and Sanxingdui were not fully surveyed until the 1960s, when it was surmised that Sanxingdui could have been one of the main centres of China's ancient Shu kingdom.

Finally, in 1980, a government archaeological team began a systematic excavation at Sanxingdui. In July 1986, the diggers discovered what is now known as Number One. In addition to jades and pottery, the most intriguing discoveries were a series of bronze heads, pointed helmets, masks and other headgear. Then, about a month later, Number Two revealed its treasures - numerous urn-shaped bronze wine vessels, bronze heads, and a huge bronze mask measuring over 130cm across.

Chen De'An, chief archaeologist and now assistant director of the Sanxingdui Museum, is quoted as describing his reaction upon first seeing the artefacts in Number Two: "I couldn't believe the way the eyes on that one mask popped out so far from the sockets. The feeling that they were staring at me kind of addled my brain. I had no idea what we were looking at."

The items from the two burial pits were compared with items unearthed earlier at Sanxingdui. Results of carbon-14 dating later indicated that the relics had been buried some 3,000 years ago, when the Shang culture flourished in the Yellow River region.

And the story is ongoing. In 2001, road-workers at Jinsha, on the outskirts of Chengdu, discovered several pits containing relics remarkably like those at Sanxingdui - ivory, jade artefacts (including the largest bi, a kind of ceremonial jade disc, ever found), and objects of bronze, gold and carved stone. While the Jinsha site has still to be thoroughly investigated, it is sure to throw up still more riddles and clues.

To find out more, I take a trip to Guanghan, about 50 minutes by bus from Chengdu's NE bus terminal. Guanghan is an eye-catching city, with tree-shaded boulevards and a business centre looking like a big Chinese temple. From the bus station, a connector minibus travels along the scenic Duck River to Sanxingdui.

Sanxingdui Museum consists of two extraordinary main galleries, some distance from each other in extensive grounds studded with gardens and canals, plus one smaller gallery. The first gallery is a mere prelude to the main exhibition space, hidden as it is half-underground. This gallery features an introduction to Sanxingdui, and the 'moon-brilliant' civilisation of the Shu Dynasty.

Jade was regarded as a sacred stone by the Shu, and (in particular the aforementioned bi discs) was used for communication between humans and gods. Metal blades, on the other hand, were used to communicate with the mountains.

The most startling exhibits are the Sacred Tree (a scale model of the 3.5m high bronze tree in Gallery Two), described as 'an axis of the world, leading to heaven' and the money tree, presumably a forerunner of the 2,000 year-old Han dynasty legend of a magic tree that rains coins when shaken.

The birds on the sacred tree denote nature spirits, while the red birds on the money tree are meant to represent the sun and its brilliance.

Gallery Two is a remarkable structure, consisting of a spiral ramp winding upwards and inwards. On the lower levels, replicas of One and Two are supplemented by exhibits of the striking masks unearthed from the Sanxingdui sites.

These remarkable figurines look like they could have come from Mayan sources. But how? Ancient Chinese legends talk of a sage Bo Gang, who once built an aircraft and flew it. Could this be where the designs come from? Personally, I reckon they look more like set-pieces out of a bizarre Terry Gillam movie.

On a higher level still, a tableau looking like an Aztec sacrificial altar, is startling in its effect. The bronze 'high priest', wearing bushranger-style metal armour and riding on a sacred bull, is surrounded by phalanxes of peons, each with a flat head like a prehistoric Frankenstein.

In the centre of the spiral, a scale model of the sacred tree, 3 and a half times the original size, totally dominates the museum. A modest bookshop on the fourth level offers a couple of English-language guides, but a much better and cheaper range can be found on level six.

Together with my companions Wei Fan and Shu Yun, I start to wind down from the heady heights of the Sanxingdui Museum by taking a stroll through the museum grounds. Everything seems normal. Until, that is, we get to the Yin-Yang circle, a performance space half-surrounded by tiered seating.

There is no doubting the power of this place. Standing in the Yin-Yang circle nearly blows me away. The experience proves to be totally unnerving, disarming and otherwise dismembering.

"Go stand in the circle and shout out loud," says Shu Yun.

I stand on the white circle, and shout. Nothing happens. I stand on the black circle and shout, and still nothing happens. Then I stand on the junction of the black and white segments and shout, and my voice suddenly reverberates as though a big bronze bell has been placed over my head.

The feeling is as weird as it is unexpected. Where did this bizarre effect come from? Was it caused by the same characters who buried those strange bronze artefacts thousands of years ago - or am I carrying speculation to a point where even Erik von Daniken wouldn't dare venture?

So, all I can recommend is this - go to Sanxingdui and repeat the experiment for yourself! The yin-yang circle is just one of the many mysteries of Sanxingdui that still await an explanation.

Getting there

Both All Nippon Airways and Air China fly regularly from Tokyo's Narita Airport to Chengdu. Buses leave regularly for Guanghan from Chengdu's new long-distance bus terminal, adjacent to the NW terminus of city bus route one. The trip to Guanghan is fast, comfortable and inexpensive (13 Yuan/RM6). From Guanghan, a minibus to the grounds of Sanxingdui Museum costs one Yuan.

MUSEUM ADMISSION Admission is not cheap, at 100 Yuan (RM47) or 50 Yuan (RM23) concession, but the money is well-spent. An English-speaking guide is 100 Yuan extra, but is not really necessary, as the exhibits are well-labelled in English. For enquiries, call +86 838 550 0439.