Seeking a legendary lost city

On any comparative scale, the temple of Sdok Kak Thom is of modest size. Its ruined sandstone sanctuary and associated reservoir lie 130km north-west of Angkor, just on the Thai side of the border with Cambodia. It belonged to a noble family that, for nine generations, had dedicated their service to the Angkorian royal dynasties, beginning in AD 800 with the founder King Jayavarman II and ending with the reign of Udayadityavarman II 250 years later. It was there that, beyond any doubt, the most important stone inscription documenting the history of Angkor was discovered in the late 19th century. Numerous scholars have pored over and given their versions of the meaning of the Sanskrit and Old Khmer lines carved on a sandstone stela that stood 1.51m high. One cannot see it any more: it was destroyed in a fire that swept through the Thai National Museum in 1958, but copies survive in Paris.

The plan of Banteay as it emerged from the jungle thanks to LiDAR. IMAGE: courtesy Jean-Baptiste Chevance.

The stela was set up on 8 February 1053, following a difficult episode in Angkor’s history, which saw a civil war involving three rival rulers following the death of the last king of the first dynasty. Suryavarman I was triumphant and established, as I have called it, the Dynasty of the Sun Kings, to reflect his name: ‘protégé of the sun’. The civil war had been very disruptive. There had been looting, pillage, and social upheaval. There are records of a most heinous crime, rooting up the boundary markers of land ownership, for which those guilty were impaled. And in the aftermath of war, as peace was restored, the noble family of Sdok Kak Thom under its patriarch Sadasiva set up this text to proclaim their 250-year loyalty to the crown and rights to their land.

Among a myriad of fascinating insights into the relationship between a noble family, its retainers, and the crown, there is a priceless section that has for long been the key evidence for the very foundation of Angkor. It describes how a king Jayavarman, meaning ‘protégé of victory’, came from afar to the northern shore of the Great Lake, the Tonle Sap. His long march began at his princely base, which has provisionally been identified at the huge, moated site of Banteay Prei Nokor on the left bank of the Mekong River. The text describes how he progressed northwards up the river, then wheeled to the west, conquering his enemies as he went, and settling land on his loyal generals.

One of his aims might have been to endow his supporters with the rich ricelands of Battambang. Thence, he moved to the northern littoral of the Great Lake, relocating his centre several times from places named as Hariharalaya to Amarendrapura, then up the Kulen Plateau and, finally, to Hariharalaya again. Tracing these moves archaeologically would be a fascinating exercise. The Kulen Plateau was seen by the Angkorian rulers as a holy upland from which sprang the perennial rivers that were diverted to feed the massive royal reservoirs. It is today still a magic place, the clear streams flow over rocky riverbeds carved with deities and hundreds of linga, the phallic symbols of fertility. The inscription describes how, on that upland, Jayavarman II was proclaimed the Chakravartin, or Universal King. Shadowy as he appears through retrospective inscriptions, he still occupies a central position in the history of Angkor, because he was regarded for centuries after his death as he who founded the state, on the traditional date of AD 802.

In the jungle

The Kulen was known to the people of Angkor as Mahendraparvata, ‘the mountain of great Indra’. Its thick forest cover makes archaeological exploration difficult indeed, a quest exacerbated by the laying of landmines by the Khmer Rouge, who holed out there during the last months of their ghastly subjection of Cambodia. During the 1930s, French archaeologists were attracted to the Kulen and the prospect of hunting down Jayavarman’s early capital. A scattered number of brick foundations were revealed, but little of moment. Until recently, the challenge to put some archaeological evidence alongside the words of the Sdok Kak Thom inscription has remained unmet. However, Jean-Baptiste Chevance has cut a Gordion Knot by applying first LiDAR (laser imaging, detection, and ranging), and then ground-truthing, to tracking down Jayavarman’s capital.

For the LiDAR survey, a helicopter flew over the target area, shooting millions of lasers down to earth, some of which penetrated the jungle and bounced back to record the surface below. With stunning clarity, LiDAR has delineated a lost city laid out, with north–south and east–west roadways covering 10km by 15km that divide the terrain into residential blocks. At the centre lay the royal palace, known as Banteay, while the unfinished temple pyramid of Rong Chen, where Jayavarman was consecrated supreme ruler on earth, lies to the south. Two massive walls on the same orientation as the roadways were part of an unfinished baray or reservoir that would have inundated 1,050m by 330m. Excavations have provided radiocarbon determinations that date this city in the reign period of Jayavarman II. There are many questions requiring further enquiry, not least the energy expended in the construction of a reservoir of such magnitude in a terrain unsuited to extensive rice production. And why after such a brief occupation was this unfinished city abandoned when Jayavarman returned to the lakeside centre of Hariharalaya? I wonder if he had made a strategic error, choosing a sacred but elevated plateau for his capital, setting in train the construction of a huge reservoir, but in a region without sufficient land for rice production.

In a decade, LiDAR has literally revolutionised our understanding of the Angkorian civilisation. Angkor Thom is a walled city built by the seventh Jayavarman, who reigned from 1181 to c.1220. It was visited by Zhou Daguan, a Chinese diplomat, for an extended period in August 1296 until July of the following year. Thankfully, he wrote a fascinating description of the city. He described a royal progress by King Indravarman, the protocols surrounding audiences in the palace, city life, and many scenes and incidents beyond the city walls. When the first Portuguese missionaries came to this same city three centuries later, it was virtually deserted. Now, apart from the central precinct, the city is still covered in thick forest, a prime target for LiDAR.

What we see as the computer-generated images develop, is a precise grid of streets and canals, house mounds, and the very ponds that Zhou Daguan saw, noting how often the inhabitants bathed in the heat of the day. By counting the ponds, colleagues estimate an urban population of at least 750,000 people. Beyond the city walls, there were suburbs again laid out in a precise grid that cover the area leading south to Angkor Wat. This most famous of all the monuments of Angkor, has also been one of the most enigmatic. It was constructed as the temple mausoleum of Suryavarman II, who was crowned in 1113. Again, apart from the central temple, the interior is covered in a thick forest. I have wandered through it more than once, and am not alone in wondering what once lay between the broad moat and the central towers. Was it an open space? Or did people live there? We now have the answer. There is a grid pattern of streets, mounds, and ponds there too. Perhaps the priests, dancers, cleaners, and cooks who serviced the mausoleum lived on site.

LiDAR has also thrown up some unanswered questions. Immediately to the south of Angkor Wat’s moat, there is a configuration of rectangular raised banks that defy explanation. Excavations have not identified any possible use. Were they a royal garden where the king and members of his court could stroll, as at Versailles, or Pall Mall under Charles II? The Angkorian landscape was also dotted with what we call mound fields, precisely laid out rows of large circular mounds where, again, excavation has not come up with any likely uses. Out beyond Angkor at the early 10th-century capital of Koh Ker, Jayavarman IV had a dam constructed fully 7km long to arrest the flow of the Rongea River, thus creating one of the largest reservoirs in the history of Angkor. There were many smaller ponds too, and many areas thick with bunded ricefields. Far to the north at Phanom Rung in North-east Thailand, I have been involved in a project to examine this great temple, perched atop an extinct volcano. LiDAR has penetrated the jungle and revealed more concentrations of mound fields.

Whoever would have imagined, when the Sdok Kok Thom inscription was first translated, that the very temple in which Jayavarman II was consecrated supreme leader on earth, not to mention his palace, streets, and unfinished reservoir, would one day, as by magic, emerge as a ghostly plan from under the Kulen jungle?