Indravarman I Conquers the Thai and the Mons Summary

  • Last updated on November 11, 2022

Based on stone inscriptions praising rule, military prowess, and conquests of Indravarman I that have been found in northeastern Thailand, many scholars believe that this Khmer king conquered the Thai and Mon peoples and enlarged the boundaries of his empire.

Summary of Event

Much of the exact nature of Indravarman I’s military conquests is still a mystery to contemporary historians. From stone inscriptions, archaeological evidence, and foreign sources, it is known that during his reign, this Khmer king at Angkor ruled over an area in northeastern Thailand and lower Laos peopled by Thai and Mons. Unfortunately, the names and dates of the battles have not been discovered, so that the individual events of Indravarman I’s conquest remain unknown. [kw]Indravarman I Conquers the Thai and the Mons (877-889) [kw]Thai and the Mons, Indravarman I Conquers the (877-889) [kw]Mons, Indravarman I Conquers the Thai and the (877-889) Indravarman I Thai;Khmer conquest of Mons;Khmer conquest of Khmers Southeast Asia;877-889: Indravarman I Conquers the Thai and the Mons[1040] Expansion and land acquisition;877-889: Indravarman I Conquers the Thai and the Mons[1040] Government and politics;877-889: Indravarman I Conquers the Thai and the Mons[1040] Wars, uprisings, and civil unrest;877-889: Indravarman I Conquers the Thai and the Mons[1040] Jayavarman II Jayavarman III Indravarman I

Indravarman I was not the son of his predecessor, Jayavarman III, but the great-nephew of Jayavarman II Jayavarman II[Jayavarman 02] , the founder of Khmer’s Angkor Angkorean period civilization. This illustrious great-uncle had established a new Khmer dynasty by conquest. He finally moved the capital to the area where later kings would build the impressive temple complex of Angkor Wat Angkor Wat . It lies next to the present town of Siem Reap at the Tonle Sap, or great lake, in the heart of Cambodia.

How Indravarman I became ruler of Khmer remains unclear. His own inscriptions claim that his grandfather, Rudravarman Rudravarman (fl. late eighth/early ninth century) was a local king. However, nothing is known of such a kingdom, and he may have been just a chieftain. One of Rudravarman’s nieces became one of Jayavarman II’s wives and bore him the future king, Jayavarman III Jayavarman III[Jayavarman 03] . Some scholars believe that Jayavarman III himself fought his way to the throne, eliminating his half brothers. Because early royal succession may have been rather violent, some historians believe that Indravarman I usurped kingship and might even have killed his predecessor, but there is no concrete historical proof of this.

A detail from the Leper King Terrace at Angkor Wat, built in the twelfth century during the reign of Jayavarman VII, who ruled the Khmer empire three centuries after Indravarman.


Most likely, Indravarman I’s family had allied itself with Jayavarman II. Jayavarman II’s initial push northwest out of a likely starting point in the upper Mekong Delta, near today’s Vietnamese city of Long Xuyen, in all likelihood continued after his death around 850. Very little is known about any concrete events in the reign of his successor, Jayavarman III. Even the beginning of his rule is disputed. Man Chu (Man Ch’u), a Chinese chronicler, visited Khmer from 861 to 863 and reported that its king ruled over vast Thai and Lao lands. For 875 or 880, the Arab traveler Ya Kubi attests to the power of the Khmer king, who received homage from local Thai and Lao lords.

This contemporary historical evidence helps establish the fact that the Khmer kings had conquered Thai and Mon lands by the time of Indravarman I’s reign. When Indravarman I became king in 877, he followed the ritual established by Jayavarman II in 802 and declared himself devaraja. This Sanskrit phrase can be translated as “god-king,” “king of gods,” or “universal monarch.” Obviously exaggerated, the claim is nevertheless grounded in the holder’s rule over a significant part of Southeast Asia.

The third Angkorian king, Indravarman I was the first to extensively commission inscriptions celebrating his glory and achievements. Because his predecessors left no such records, it is hard to distinguish their individual contributions to the rise of the Khmer empire of the Angkor era. This era is commonly dated from 802 to 1431, when Angkor Wat was abandoned. However, by the time Indravarman I became king, or very shortly after, he ruled over vast stretches of Thai and Mon territory.

As king, Indravarman I lived in a palace at Hariharalaya (now Roluos). It lies very close to the later Angkor Wat. Two years after he became king, Indravarman I completed the temple complex Preah Ko Preah Ko (Sanskrit for “sacred cow”). The temple honored his parents and ancestors, and its inscriptions contain the earliest records of his military achievements.

The inscriptions at Preah Ko state that Indravarman I came to power through successful conquest and military valor. He is described as a fierce yet compassionate warrior:

The right hand of this prince, long and powerful, was terrible in combat when his sword fell on his enemies, scattering them to all points of the compass. Invincible, he was appeased only by his enemies who turned their backs in surrender, or who placed themselves under his protection.

Another inscription at the temple reads: “In battle, which is like a difficult ocean to cross, he raised a pathway, made up of the heads of his arrogant enemies; his own troops passed over on it.” However, it is not written who these enemies were. Some scholars believe that the passages could refer to both external adversaries such as the Thai and Mons and Khmer rivals.

The clearest indication for Indravarman I’s victories over other people in Southeast Asia also comes from Preah Ko: “It seems that the creator [Indra], tired of making so many kings, had fashioned this king Indravarman to form the joy of the three worlds, uniquely.”

The new king’s very name means “protected by Indra,” with Indra the name of the creator in Hinduism. Indravarman I may have used a name that expresses his rule over many different people in his empire, whose many kings he replaced with himself alone.

A different inscription at a temple far away from the capital attests the reality of territorial conquest not so much by its words but by its geographical location in recently conquered territory. The inscription calls Indravarman I “ruler of the entire world” and claims that “atop the lordly heads of the kings of China, Champa, and Yavadvipa his reign was like a flawless crown,” meaning that these kings obeyed him. Historians have fiercely debated this claim. The Khmer state did not rule over China; most likely the area meant was in Laos, a country that borders China to the south, and included land in northern Thailand. Champa refers to an indigenous kingdom in present-day southern Vietnam. Scholars hotly discuss where Yavadvipa was located. Some think it is Java, in Indonesia, others believe it lies in the Mekong Delta.

Because the remaining inscriptions of Indravarman I’s reign speak of peace and the prosperity of his subjects, it appears that any conquests made by this king must have occurred either during the reign of Jayavarman III, in a period of civil war following Jayavarman III’s death, or in the two years from 877 to 879 when Preah Ko was completed. Most scholars believe that Indravarman I fought to successfully expand the Khmer empire under its second king, whom he may have deposed by force, and celebrated his victories by crowning himself king in 877.


Regardless of the exact historical circumstances of Indravarman I’s conquest and the exact degree of his military contribution to the rise of Cambodia’s Angkorian empire, it is clear that this king ruled over a large stretch of Southeast Asian land that included many Thai and Mons who had been conquered. By the time of his death in 889, Khmer had established a strong empire that would flourish for more than five hundred additional years. His ambitious building program and his commission of inscriptions celebrating his glory created a pattern for his successors.

The Khmer conquest of Thai and Mon people and their territory created the material base for the rise of a remarkable civilization. Indravarman I solidified the young empire and established the styles for the religious buildings through which its rulers sought to immortalize themselves.

However, the violence of his early years also contained the seeds for the eventual fall of the Angkor civilization. Conquered people fought to free themselves. Another ongoing problem was the recurring violent struggle for royal succession that may have also plagued Indravarman I’s rise. Civil wars among princely contenders disrupted society, and foreign allies of the fighting factions would claim parts of the empire.

Indravarman I left behind a strong empire. Through his inscriptions and stone reliefs depicting life during his reign, much of his culture has survived for posterity. Conquered foreign workers aided his building program. Soon, the Khmer would build one of humanity’s most astonishing temple complexes at Angkor Wat, close to Indravarman I’s temples.

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Briggs, Lawrence Palmer. The Ancient Khmer Empire. 1951. Reprint. Bangkok: White Lotus Press, 1999. Groundbreaking description of the Angkor kings and the basis of much later writing. Discusses all of Indravarman I’s inscriptions with a map of their location. Genealogical table, strong focus on art and architecture. Illustrated.
  • citation-type="booksimple"

    xlink:type="simple">Chandler, David P. A History of Cambodia. 3d ed. Boulder, Colo.: Westview Press, 2000. Chapter 2 provides a very informed and readable portrayal of the early Angkor kings. Maps, illustrations.
  • citation-type="booksimple"

    xlink:type="simple">Coedès, George. The Indianized States of Southeast Asia. Translated by Walter Vella and Susan Brown Cowing. Honolulu: East-West Center Press, 1968. Influential study. The chapter on “The Kingdom of Angkor” offers a useful overview. Illustrated, maps.
  • citation-type="booksimple"

    xlink:type="simple">Ghosh, Manomohan. A History of Cambodia. Rev. 2d ed. Calcutta, India: Calcutta Oriental Book Agency, 1968. Portrait of Indravarman I’s reign from a non-Western perspective.
  • citation-type="booksimple"

    xlink:type="simple">Hall, Daniel. A History of Southeast Asia. London: Macmillan, 1981. 4th ed. The chapter on “The Khmers and Angkor” reveals a solid survey of the rise of the Angkor civilization.
  • citation-type="booksimple"

    xlink:type="simple">Higham, Charles. The Civilization of Angkor. London: Weidenfeld and Nicolson, 2001. Competent portrayal of Indravarman I and his reign, places the king well in the context of his rising civilization. Photos, maps.

Categories: History