Archaeologists approach the Thom Dab temple in the Siem Reap region. Credit:Nick Moir An expedition of Australian and French archaeologists using GPS co-ordinates gathered from the instrument's data uncovered five previously unrecorded temples and evidence of ancient canals, dykes and roads. The Saturday Age recorded the discoveries by joining the expedition as it pushed through landmine-strewn jungle, swollen rivers and bogs on a mountain called Phnom Kulen, 40 kilometres north of Angkor Wat in north-western Cambodia. French-born archaeologist Jean-Baptiste Chevance, director of the London-based Archaeology and Development Foundation, a co-leader of the expedition, said it was known from ancient scriptures that the great warrior Jayavarman II had a mountain capital ''but we didn't know how all the dots fitted, exactly how it all came together''. ''We now know from the new data the city was connected by roads, canals and dykes,'' he said.

Mahendraparvata existed 350 years before Angkor Wat, the Hindu temple that has captivated interest across the world and attracts more than 2 million people a year. The lidar technology effectively peeled away the jungle canopy by using billions of laser impulses, allowing archaeologists the first glimpse of structures that were in perfect squares, completing a map of the city that years of painstaking ground research had been unable to achieve. The archaeologists were amazed to see that 36 previously recorded ruins scattered across the mountain were linked by a network of gridded roads, dykes, ponds and temples that were divided into regular city blocks. Over a period of years Dr Chevance and his staff had crossed ancient roads and passed by ancient structures they suspected were there but could not see because they were hidden by jungle and earth. The discovery will prompt scientific excavation of the area's most significant sites by archaeologists seeking to discover what life was like for a civilisation about which virtually nothing is known, including why it was abandoned to the forest.

It also will allow archaeologists and historians to learn more about the evolution of Angkor, the enormous political and religious empire that dominated most of south-east Asia for 600 years. The director of the University of Sydney's centre in Cambodia, Damian Evans, who was another leader of the expedition, said there may be implications for modern society. Loading ''We see from the imagery that the landscape was completely devoid of vegetation,'' Dr Evans said. ''One theory we are looking at is that the severe environmental impact of deforestation and the dependence on water management led to the demise of the civilisation … perhaps it became too successful to the point of becoming unmanageable.''