Henri Mouhot, made an expedition into the interior of Indo-China in 1860 to study the plant forms that nature had evolved there. Walking along a narrow jungle path one steamy morning, he turned a corner and saw through the trees a fantastic tower of grey stone. As he moved forward, other towers appeared, grouped around the first. He had heard stories of overgrown temples in the area, but this was beyond all imagining. He had rediscovered Angkor Wat, the largest temple in the world, lost and overgrown for centuries after its sacking in 1431.

During the decades after Mouhot's discovery, archaeologists followed his path to central Cambodia. They cut back the smothering vegetation and found around the Angkor War temple the remains of the vast city at the centre of the Khmer kingdom. This was, at times, the most powerful force in Asia-bar the Chinese empire-during the period when Europe was emerging from the Dark Ages. That city was Angkor, the Khmer capital for most of the six centuries after A.D. 800. The plain of central Cambodia, the country now known as Kampuchea, is a hothouse where life-giving water and the richness of the alluvial soil are counter-balanced by the torrid heat of the wet season, the roaring floods that leave pools to stagnate and rot until the next monsoon and the creatures of all sizes that bite and sting. It was to this fertile hell that the Khmers moved down the great Mekong river from their sandstone mountains in the north when they annexed the declining kingdom of Funan at the end of the eighth century.

The Mekong, forcing its waters deep into a gorge through the mountains, created the Cambodian plain and still controls much of its weather and agriculture. Its massive basin collects the melting mountain snow in spring and swirls the water down to the land it has flattened over the millennia. There on the plain, the Mekong floods its normal banks and reverses the flow of lazy tributaries. One of these, the Tonle Sap, flows vigorously upstream at this season .A little later, in May, the monsoon starts its six months of steamy downpour. So floods, rain and heat dominate life for those months and the dry season comes in November.

It was this rhythm of life, especially the violent extremes in the calendar of the Great Lakes, that the Khmer people had to harness for their civilization to flourish. These people, the Khmer, were the same distinct group as the Cambodians today, for they have remained separate for thousands of years despite the constant struggles between the rival nations of South-East Asia. The population of Indo-China was formed many centuries before the birth of Christ from various mixtures of the Caucasian and Negrito people, who inhabited the Pacific islands, too, but mixed with a later wave of Mongolians from China.

Since Indo-China is divided by its formidable mountain ranges into a number of obvious regions centred on habitable plains, the people who settled in each isolated part developed individual identities. At the time when the Roman Empire had conquered the Mediterranean, the advanced civilization of India made regular contact with these Indo-Chinese nations through trade and this was to influence the way their cultures developed.