Temples, roads and Angkorian power: the Khmer imprint on the lands of the future Siam

From the Khorat Plateau to the Chao Phraya valley, stone sanctuaries are a reminder that between the 11th and 13th centuries much of present-day Thailand revolved around Angkor. Yet this hold was neither uniform nor continuous. It tightened under Suryavarman I, loosened on the death of Suryavarman II and was renewed under Jayavarman VII, before Lavo, and then the new Thai powers of Sukhothai and Ayutthaya, overturned the balance of power. Here are the sovereigns and local figures who shaped this history, seen through often fragmentary inscriptions that historians still read in different ways.

A city older than the empire

In Lopburi, some hundred and fifty kilometres north of Bangkok, visitors come across ruined stone towers at street corners, in the midst of the modern town. They are readily described as ‘Khmer’. The label is accurate, but incomplete. It conceals a longer, more layered history, one that helps us understand what the Angkorian presence really amounted to in the territories that would later form Siam.

Between the 10th and 13th centuries, three geographical areas came within the orbit of Angkor, the great capital in what is now Cambodia. The first is the Khorat Plateau, present-day Isan. The second is the Chao Phraya valley, around the city of Lavo, today's Lopburi. The third comprises a handful of places in the west, towards Kanchanaburi and Phetchaburi. The sources agree on one point: the intensity of control varied greatly from one reign to the next. To speak of a ‘Khmer empire in Thailand’ would therefore be doubly anachronistic. At the time there was neither a Thailand nor any linear border, only cities, principalities and networks of allegiance whose contours were constantly shifting.

Lavo existed long before the Khmers arrived. A hoard discovered at U Thong in 1966 contained silver coins bearing ‘lava’ on one face and ‘pura’ on the other, in a script derived from the Pallava alphabet of southern India. These coins are dated to the 7th–8th centuries. They are the earliest reliable mention of the city's name. Lavo then belonged to the world known as Dvaravati: a group of cities of Mon and Buddhist culture spread across the Chao Phraya basin. The Khmer buildings of Lopburi in fact reuse stones from older Dvaravati sanctuaries. The city's oldest ruins are thus, to borrow a common phrase, ‘Khmer in style on Dvaravati foundations’. The historian Phiset Chiajanpong goes further. He proposes identifying Lopburi with the city called Dvaravati itself, drawing on its remains and on a long tradition that makes it a gathering place for relics. The hypothesis remains debated, but it is a reminder that Lavo was not merely an Angkorian creation.

Finally, a word on vocabulary. Early Thai sources often speak of the ‘Khom’. The term is generally translated as ‘Khmers’, but whether the two are exactly equivalent is debated. The nuance matters: it is a reminder that modern ethnic categories do not always map onto those of the texts.

Suryavarman I, the usurper who looked west

The first sovereign whose activity in these territories is clearly documented is Suryavarman I, who reigned until 1050. His accession was anything but peaceful. Around 1002, he seized the throne from Udayadityavarman I. He then needed nearly a decade of war against a rival, Jayavirahvarman, to establish himself around 1010. According to the work of Michel Jacq-Hergoualc'h, this conflict was linked to the campaigns waged on the Khorat Plateau and in the Chao Phraya basin. The conquest of the west and the struggle for power at Angkor were therefore closely intertwined.

His inscriptions display a revealing feature: they do not link him to his predecessors. This points to a legitimacy that had to be built rather than inherited. A Mahayana Buddhist, he was also tolerant of Theravada Buddhism, then gaining ground in the region. This openness was probably not without significance in territories of Mon and Buddhist tradition such as Lavo.

The decisive step came in 1022. An inscription of Suryavarman I, discovered at Lopburi, names the city ‘Lvo’ and describes its inhabitants as Khmers. Lavo thus entered the administration of the empire. What was at stake was not merely territory. Through Lavo, Angkor gained access to the trade routes of the Isthmus of Kra, the narrow passage between the Gulf of Thailand and the Andaman Sea through which goods and merchants travelled between the Indian Ocean and the China Sea.

This advance may have had repercussions far beyond the Chao Phraya. According to a hypothesis put forward tentatively, around 1025–1026 Suryavarman I may have campaigned against a Lavo that was then a vassal of Tambralinga, a principality on the Malay Peninsula. This would have been one of the causes of a wider conflict pitting Tambralinga and Srivijaya against Angkor and the Chola dynasty of southern India. None of this is established with certainty, but the hypothesis sheds light on an essential point: Lavo stood at the junction of several worlds, Khmer, Mon and Malay.

The very origins of Suryavarman I were long debated. George Cœdès, a leading figure in Southeast Asian epigraphy, had initially suggested that he was the son of a king of Nakhon Si Thammarat, on the peninsula. He relied on northern chronicles: the Tamnan Mulasasana, the Jinakalamali and the Camadevivamsa. These are religious and dynastic texts written long after the events. In his 1965 study with Jean Boisselier, translated into Thai by Subhadradis Diskul, Cœdès no longer upholds this thesis. The same study presents so-called ‘Lopburi’ art as heir to Dvaravati art, rather than as an art simply imported from Cambodia. This change of mind encapsulates a broader shift in scholarship: researchers stopped seeing the Khmer remains of the Chao Phraya as a foreign graft and began to read them as a local synthesis.

The 12th century: an overlordship that tightens and loosens

At the end of the 11th century, the centre of gravity of Angkorian power shifted in a way that directly concerns Isan. A new line, known as the Mahidharapura dynasty, came to the throne with Jayavarman VI, followed by Dharanindravarman I. According to the most widespread interpretation, this family originated on the Khorat Plateau, north of the Dangrek Mountains. Its precise roots, however, remain debated. If this origin is accepted, the plateau was no longer a conquered periphery. It became the cradle of a dynasty that would rule over Angkor.

It is in this context that the great sanctuary of Phimai, the ancient Vimayapura, is usually placed. It is a Mahayana Buddhist temple whose main sanctuary is generally dated to the turn of the 11th and 12th centuries; the precise date has yet to be confirmed. Further south, Phanom Rung, perched on an extinct volcano in Buriram province, is associated by an inscription with a local lord, Narendraditya, related to the Mahidharapura line, and with his son Hiranya. These two prasat (tower sanctuaries in the Khmer tradition) bear witness to powerful regional elites capable of commissioning monuments of the first rank. Here the Angkorian imprint appears less as an occupation than as the work of local aristocracies integrated into the Khmer world.

At Lavo, the story is more turbulent. Thai historiography places there a sovereign, Sri Dharmasokaraja I, whose effective reign is said to have ended around 1117. This date coincides with the expansion of the Mahidharapura dynasty under a king named ‘Sri Jayasinghavarman’. The latter is commonly identified with Suryavarman II, who reigned from 1113 to 1150, but the identification is not certain. Reference works also credit Suryavarman II with the construction of Angkor Wat.

Relations with China offer a valuable indicator of this fluctuating authority. Lopburi sent embassies to the Chinese court in 1115, then in 1155. The second mission, shortly after the death of Suryavarman II, is generally interpreted as a sign of regained autonomy: a tightly subjugated city would not have dealt directly with the emperor. Some evidence further suggests that the empire of Suryavarman II may have fought the Mons for overlordship of the region, but this point remains tentative.

A detail at Angkor Wat shows how closely these western territories were bound up with the life of the empire. On the bas-reliefs of the south gallery, which depict a military procession, there appear a contingent from ‘Lvo’ and a group labelled ‘Syam Kuk’. Should we see them as Siamese, as mercenaries or as vassals? The question remains open. It nonetheless shows that the peoples of the west contributed to Angkorian power, whatever their status.

Jayavarman VII: roads, rest houses and a prince at Lavodaya

After a period of unrest, Jayavarman VII ascended the throne in 1181 and reigned until around 1218. This was the last great moment of Angkor's hold over Lavo, and it is documented by an exceptional source. The Phimeanakas inscription at Angkor mentions, in its 57th stanza, a son of the king, born of Queen Jayarajadevi, described as ‘lord of Lavodaya’. Jayavarman VII would thus have entrusted Lavo to a member of his own family, marking a far closer form of control than mere overlordship.

The stone, however, is incomplete. The beginning of the prince's name is missing: only the end survives, ‘…tindravarman’. It was Cœdès who restored it as ‘Nripatindravarman’. The existence of a king of Lavo by this name until 1218 should therefore not be taken for granted: it remains a scholarly hypothesis. Under this same reign, the city's name is written Lvodayapura.

In reference works, the reign of Jayavarman VII is also associated with a policy of equipping the territory. The most widespread reading credits him with a network of arogyasala (hospitals) and dharmasala (staging posts, sometimes called ‘houses of fire’) set at intervals along the royal roads. Prasat Ta Muen, on the route linking Angkor to Phimai, is said to be one example. The Preah Khan inscription at Angkor also lists statues of Jayabuddhamahanatha sent to various towns. Some historians identify several of these with cities in present-day Thailand, such as Lopburi, Mueang Sing or Phetchaburi, but these identifications are debated. Finally, several monuments are linked to the so-called Bayon style, specific to this reign: the Prang Sam Yot in Lopburi, the prasat of Mueang Sing in Kanchanaburi and Wat Kamphaeng Laeng in Phetchaburi. Here prang refers to a tower sanctuary with a rounded profile, which would become a major element of Siamese architecture.

If these attributions are accepted, they outline a conception of power founded on circulation. Roads, staging posts and religious images radiating out from the capital gave material form to the sovereign's authority far more than any border. But this was also the moment when that authority reached its limits.

From vassal to successor: Sukhothai, Lavo, Ayutthaya

In the 13th century, new Thai-speaking principalities asserted themselves in the Chao Phraya valley and on its fringes. Inscription No. 2, known as the Wat Si Chum inscription, at Sukhothai, is a key document. Among other things, it recounts the restoration of a great reliquary by a monk, Phra Maha Thera Si Sattha. According to the usual reading, it also relates that Pha Mueang, a Thai chief, received from a Khmer king a title, a wife and a sword, before helping Bang Klang Hao, the future Si Inthrathit, to take Sukhothai. This account must be read for what it is: a text of legitimation, written by and for a lineage. It nonetheless shows that the first Thai powers still defined themselves in relation to Khmer authority, claiming it as much as breaking free from it.

Still, one needs to know what the texts mean by ‘Khmer’. In 1983, Sujit Wongthes argued that the ‘Kamboja’ of northern texts, such as the Jinakalamali, the Northern Chronicle or the Kalyani inscriptions, refers to Lavo and a group of related towns, such as Sukhothai, Sawankhalok or Phichai, and not to Cambodia. In his view, systematically translating it as ‘Cambodia’ led historians to treat Lavo as a mere Khmer dependency. The 1022 inscription, which describes the inhabitants as Khmers, argues rather for genuine integration, at least at that time. The debate remains open. It obliges us to think of Lavo as an entity with its own continuity, and not as a passive province.

This continuity shows clearly at the end of the 13th century. According to Cœdès, Lavo ‘broke away from Cambodia’ between 1289 and 1299 and sent its own embassies to China. Chinese accounts from the same period, including that of the traveller Zhou Daguan, are often cited as evidence of wars between Angkor and the Siamese; this point has yet to be confirmed in the text itself. In the 14th century, a new power absorbed the old city. According to the phongsawadan (Siamese royal chronicles), Lavo was annexed around 1350 to the kingdom of Ayutthaya, under its founder Ramathibodi I. The city then took the Thai name Lopburi. As is often the case, the chronicles do not always agree on dates: 1350 or 1351, depending on the version.

The balance of power then reversed. Historiographical tradition credits Borommarachathirat II, king of Ayutthaya, with the capture of Angkor, generally dated to 1431. Both the date and the scale of the event are debated by historians: was it a lasting conquest, a raid or an episode magnified by the chronicles? Whatever the answer, the former overlord had become the target of a kingdom that had grown partly out of its old margins.

Lopburi did not disappear for all that. In the mid-17th century, King Narai made it a second capital and resided there for much of the year. The prang inherited from the Angkorian era then stood alongside the palaces of a Siamese sovereign in contact with Persia, China and France. The Khmer imprint had become one of the layers of a Siamese royal landscape.

What we see today, and what remains open

The heritage recognition of these sites reflects their singular place in the national narrative. In 2019, the ensemble formed by Phanom Rung, Mueang Tam and Plai Bat, in Buriram province, was added to Thailand's UNESCO Tentative List, the antechamber to a possible World Heritage nomination. The Bangkok Post reported this listing together with that of Si Thep Historical Park. The same year, Phimai was removed from the Tentative List; the sources consulted do not give the reason. Most of these sanctuaries were restored during the second half of the 20th century under the aegis of the Fine Arts Department, Thailand's heritage authority, sometimes in collaboration with foreign partners. The details of this work are best consulted with the institution itself.

Standing before a prasat in Isan or a tower in Lopburi, then, three things should be borne in mind. The first is the layering of periods: beneath the Khmer stone a Dvaravati sanctuary often shows through, and around it stretches a Thai town. The second is the variety of actors: the kings of Angkor, of course, but also the aristocracies of the Khorat Plateau, Mon cities, principalities of the peninsula and Thai chiefs, each using Angkorian prestige for their own ends. The third is the fragility of the sources: a mutilated stanza, a restored name, a late chronicle or a word such as ‘Kamboja’ is enough to alter the overall picture.

The history of the Khmer imprint is therefore not one of domination followed by decline. It is that of a shifting relationship, made up of integration, vassalage, negotiation and bids for autonomy. It ends with the emergence of kingdoms, Sukhothai and then Ayutthaya, which inherited this world as much as they broke away from it.

Sources and further reading

1. Contributeurs Wikipédia, Lopburi, Wikipedia (en), consulté 2025.
2. Contributeurs Wikipédia, Lavo Kingdom, Wikipedia (en), consulté 2025.
3. Contributeurs Wikipédia, Sri Dharmasokaraja I, Wikipedia (en), consulté 2025.
4. Contributeurs Wikipédia (d'après G. Cœdès), History of Lopburi, Wikipedia (en), consulté 2025.
5. Contributeurs Wikipédia (d'après M. Jacq-Hergoualc'h, 2002), Jayavirahvarman, Wikipedia (en), consulté 2025.
6. Contributeurs Wikipédia, Nripatindravarman III, Wikipedia (en), consulté 2025.
7. Contributeurs Wikipédia (d'après Cœdès ; Walailak University), Suryavarman I, Wikipedia (en), consulté 2025.
8. Contributeurs Wikipédia, Lopburi province, Wikipedia (en), consulté 2025.
9. non indiqué, UNESCO World Heritage Sites in Thailand (Tentative List), worldheritagesite.org, consulté 2025.
10. Bangkok Post, Two sites placed on Unesco 'tentative list', Bangkok Post, 2019.