A picture is worth a thousand words - or so goes the cliche. To a historian, the premium is often higher. A picture can be an irreplaceable record of a place, an event, a custom, a personality. In the case of a country like Laos, where there are few written records and where much of the material evidence of the past has been lost, the pictorial record becomes priceless.

That is exactly the significance of this exhibition and the book which accompanies it, ‘The Basin of the Mekong River - Images of the Past’. The book, published in 1996, contains 147 maps, engravings and photographs from the countries bordering the Mekong made between 1571 and 1937, while the exhibit includes 40 additional images.

The show has been curated by French academic Dr Bernard Gay, a historian who has been visiting Laos since 1974. "No one has put together an exhibition of photographs like this before," says Dr Gay. Through the exhibition, he says, many young Lao people have seen images of their own past for the first time.

Dr. Gay enthuses about the ethnic and cultural diversity of the Mekong region, which he has sought to highlight in the display. "You cannot find any other part of the world with five independent language families or with as many separate cultures and religions," he says. That diversity is expressed in images of Tibetan nomads clad in sheepskin, girls arrayed in the silk finery of Luang Prabang, and near-naked hunters sporting crossbows near the Cambodian-Lao border, to name just a few.

Some of the pictures look like they might have been taken yesterday. Others look like they are from a different world. Still others are an intriguing blend of old and new. And many of them are beautiful photographs in their own right.

Take the picture, ‘Morning Market, Vientiane, 1910’. Two open-sided market buildings, recognisably French with their square pillars and shingled roofs, converge on either side of a road which runs through the middle of the frame. The centre is a delicate combination of stillness and movement, as two boys in starched pyjamas and sola topees hold their bicycles and watch the bustle of the market.

I had been looking at the picture for a few minutes before I realised why it seemed so familiar - it was Pangkham Street in the centre of the city, viewed from the point where the Namphou fountain now stands. The market buildings have disappeared, replaced by concrete shophouses occupied by tailors and shoe stores, but the elegant cloistered buildings at the extreme edge of the frame still stand. With the help of this one outstanding photo, the entire streetscape of 1910 can be reconstructed.

Other pictures provide a unique record of things that have disappeared - such as the photo of the king of Muang Sing with his court, taken in 1894, two years before the principality was incorporated into the French administration. Or the picture of a ‘love court’ at a wat in Luang Prabang, where youngsters would gather to woo each other with poetry and song. Some of the photos of hilltribes in their traditional costumes, on the other hand, could be taken today.

The exhibition and the book grew out of activities to mark the 200th anniversary of the National Institute of Oriental Languages and Civilisations in Paris. About 10,000 old photos and engravings have been collected over the last five years by Dr Gay. The images were gathered from over 30 different national collections in France, Britain and Thailand, while many of the maps came from Portugal and the Netherlands.

Many of the pictures are from early colonial expeditions up the Mekong. The earliest engravings are those by Louis Delaporte, the talented young artist who acompanied the first Western attempt to explore the river, the Lagree expedition of 1866-8. One interesting engraving shows the market at Luang Prabang in 1867, complete with Phousi hill in the background. Another recalls the custom among men of northern Laos of tattooing the abdomen and thighs, which has now died out.

The exhibition has already toured in Vietnam, Malaysia, Cambodia and the Philippines, while a larger version is on display at the East-West Centre in Hawaii. Dr Gay hopes to keep touring the display - while continuing to add to it - to as many countries as possible. Part of the collection will go on permanent display at the planned Heritage Centre in Luang Prabang. A book of photos entirely from Laos is also in the pipeline.

The exhibition catalogue is a handsome soft cover edition published by Diagonale. It makes an excellent souvenir of Laos, and an invaluable historical guide when sightseeing.

The pictures are divided into five categories - the river, ethnic groups, daily life, colour reproductions (of engravings), and beliefs and festivals. My one criticism of the book is that the captions are all at the rear, instead of beneath the photos. It makes for an elegant look but a frustrating browse. The images have also not been placed in numerical order of their captions, which is a little confusing.

In the photograph on the cover of this book, a line of tiny figures crosses the 16th century suspension bridge in China’s Yunnan Province. They are dwarfed on all sides by the walls of a massive gorge, while beneath them the waters of the Mekong surge with the strength of a mountain torrent.

The image says much about humanity’s relationship with this river. Used for centuries as a trade route, the Mekong is nevertheless wild water for much of its course, acting as a barrier as much as a highway.

The 400 year old chain bridge was destroyed by a flood in the 1980s. Nowadays, there is little left but the stone abutments on either bank. And this is why this book is important.

‘The Basin of the Mekong River - Images of the Past’ brings together 147 historic maps, engravings and photographs from the countries bordering the Mekong. In a region wracked by turmoil for 50 years, the images are a rare record of a past that has in many cases disappeared forever.

The exhibition and the book grew out of activities to mark the 200th anniversary of the National Institute of Oriental Languages and Civilisations in Paris. About 10,000 photos and engravings dating from 1571 to 1937 have been collected over the last five years by Dr Bernard Gay, a historian at the Institute. The images were gathered from over 30 different national collections in France, Britain and Thailand, while early maps came from Portugal and the Netherlands. Dr Gay believes that it is the first collection of its kind to be assembled.

Many of the pictures are from early colonial expeditions up the Mekong. They are divided into five categories -the river, ethnic groups, daily life, colour reproductions (of engravings), and beliefs and festivals.

Dr. Gay has included relatively few images of Thailand in the collection, reasoning that Thailand has been well represented in previous publications. Instead, the selection favours pictures from Vietnam, Cambodia, Laos, Burma, Yunnan, and Tibet, where the Mekong has its headwaters.

Some of the photos are apposite even today. On page 171, a young boy bedecked in silk and jewels gazes confidently, almost arrogantly at the camera. Behind him, a boy with much darker skin holds up a giant parasol. "Young royal prince in ceremonial attire, in Phnom Penh. The servant holding the sunshade over his head is nearly the same age, Cambodia, 1921," reads the laconic caption.

And there lie both the strength and the weakness of this book. The boy’s look says more than words could ever capture about the hubris that afflicts the Cambodian royal family. But who is the prince? How old is he? What became of him? The captions throughout give few details, and the introduction runs to a mere three pages. It seems a pity Dr Gay did not use some of his undoubtedly prodigious research to make the book a little more informative.

Nevertheless many of the images are outstanding, and easily carry the book on their own merit. Some are of historical interest - pictures such as the 1893 view of a launch sliced in half amidships and put aboard a railway across Done Khong island in southern Laos to bypass the Khone waterfalls.

Many of the colour engravings are by Louis Delaporte, the artist who acompanied the first Western attempt to explore the river, the French expedition of 1866-8. They are beautiful if somewhat Biblical - the new moon festival in Nong Khai in 1867, for example, looks more like the product of a young man’s Richard Burton fantasy than anything I can imagine ever having happened in Nong Khai.

Some of the photos are aesthetically excellent. P. Gastaldy’s, ‘A Vietnamese nun in Cantho, Conchinchina, 1937’, which ends the book, is the undoubted masterpiece.