Ancient History's Lost Cities


Stone temples and their surroundings are the skeletons of the vanished Khmer Empire, easily visible in the jungle canopy. Scholars assumed the city’s inhabitants lived in wood-and-thatch houses mostly within the surrounding walls of the temples that form the hearts of successive capitals. It seemed all evidence of the flimsy houses was lost forever beneath the jungle.

In 2012, though, in a project of remote sensing headed by Roland Fletcher of Sydney University, new technology brought this hidden world to light for the first time. The main technique is ‘lidar’ (light + radar), in which an airborne source of laser light fires pulses at a rate of 150,000 per second, which are reflected from the ground to produce a three-dimensional map to an accuracy of under 20 centimetres (eight inches). Even over jungle, enough laser light penetrates between the leaves to provide stunningly accurate details of the ground.

The results reveal that the temples were surrounded by immense cityscapes of roads, canals, ponds, field boundaries and occupation mounds. In one of the most remarkable discoveries, the survey revealed a pre-imperial capital, Mahendrapavarta, previously known only from inscriptions. Similar finds redefine the outlying cities of Phnom Kulen and Koh Ker. Angkor Thom and its surroundings, previously thought to only cover nine square kilometres (3.5 square miles), is now seen to be set in grids of canals, roads and embankments that almost quadruple its size to 35 square kilometres (13.5 square miles). In this new view, the temples appear less as separate sub-capitals and more as ‘nodes’ of a ‘hydraulic city’ that once covered some 1,000 square kilometres (386 square miles). The findings, writes Roland Fletcher and his co-authors, are vital to help explain the growth and collapse of this unique civilisation.