Water Chenla is subjected to attacks by pirates from Java, Sumatra, and the Malay Peninsula late in the eighth century.

By the beginning of the ninth century, it has apparently become a vassal of the Sailendra dynasty of Java.

The last of the Water Chenla kings allegedly is killed around 790 by a Javanese monarch whom he had offended.

The ultimate victor in the strife that follows is the ruler of a small Khmer state located north of the Mekong Delta.

His assumption of the throne as Jayavarman II (ca. 802-50) marks the liberation of the Khmer people from Javanese suzerainty and the beginning of a unified Khmer nation.

Jayavarman II, according to an older established interpretation, was supposed to be a prince who lived at the court of the Sailendra dynasty in Java (today's Indonesia) and brought back to his home the art and culture of the Javanese Sailendran court to Cambodia.

At this time, Sailendras allegedly rule over Java, Sumatra, the Malay Peninsula and parts of Cambodia.

This classical theory was revisited by modern scholars, such as Claude Jacques and Michael Vickery, who noted that Khmer called chvea the Chams, their close neighbors.

Moreover, Jayavarman's political career began at Vyadhapura (probably Banteay Prei Nokor) in eastern Cambodia, which make more probable long time contacts with them (even skirmishes, as the inscription suggests) than a long stay in distant Java.

Finally, many early temples on Phnom Kulen shows both Cham (e.g., Prasat Damrei Krap) and Javanese influences (e.g., the primitive "temple-mountain" of Aram Rong Cen and Prasat Thmar Dap), even if their asymmetric distribution seems typically Khmer.

Jayavarman appears to have been of aristocratic birth, beginning his career of conquest in the southeast of present-day Cambodia.

After he eventually returned to his home, the former kingdom of Chenla, he quickly built up his influence, conquered a series of competing kings, and in 790 became king of a kingdom called "Kambuja" by the Khmer.

In the following years he extended his territory and eventually established his new capital of Hariharalaya near the modern Cambodian town of Roluos.

He thereby laid the foundation of Angkor, which is to arise some fifteen kilometers to the northwest.

In 802, he declares himself Chakravartin, in a ritual taken from the Indian-Hindu tradition, thereby becoming not only the divinely appointed and therefore uncontested ruler, but also simultaneously declares the independence of his kingdom from Java.

The foundation of Hariharalaya near present day Roluos is the first settlement in what will later become the empire of Angkor.

Despite this key role in Khmer history, few firm facts survive about Jayavarman.

No inscriptions authored by him have been found, but he is mentioned in numerous others, some of them written long after his death.

Southeast Asia (820 – 963 CE): Khmer Beginnings, Pyu Decline, Cham Expansion, and Srivijaya’s Maritime Power

Geographic and Environmental Context

Southeast Asia in this age stretched from the Irrawaddy, Chao Phraya, Mekong, and Red River basins to the Malay Peninsula and the great insular corridors of the Malacca Strait, Java Sea, Makassar Strait, Sulu Sea, and the Moluccas—the hinge between the Indian Ocean and South China Sea.
Two complementary realms defined the region:

• Mainland agrarian heartlands (southern & eastern Myanmar, Thailand, Cambodia, Laos, Vietnam) built on irrigated rice basins.

• Insular thalassocracies (Sumatra—excl. Aceh & West offshore islands, Java, Borneo, Sulawesi, Bali–Timor, Banda–Moluccas–Ceram–Halmahera, Philippines) that mediated the Indian–China sea-lanes.

The adjacent Andamanasia arc—Andaman & Nicobar Islands, Aceh and its offshore chains (Simeulue, Nias, Batu, Mentawai), the Cocos (Keeling), and the Preparis–Coco islets—formed the Bay of Bengal’s island threshold into the Strait of Malacca.

Climate and Environmental Shifts

A warm, humid tropical regime prevailed with monsoon regularity.

• Mainland basins enjoyed reliable flood–recession cycles for wet-rice expansion.

• Insular corridors experienced stable sailing seasons; volcanic soils in Java and Sumatra yielded high rice outputs.

• ENSO variability intermittently brought droughts and typhoons—hardest on atolls and windward coasts—yet diversified subsistence and maritime redistribution buffered shocks.

• Toward the century’s end, conditions segued toward the Medieval Warm Period without major disruption.

Societies and Political Developments

Mainland Southeast Asia

• Myanmar (southern & eastern): The Pyu city-states (Śrī Kṣetra, Beikthano, Halin) waned after Nanzhao incursions in the 9th century. Burman-speaking groups moved into the central Irrawaddy, laying foundations for the Pagan/Bagan polity of the next age; Pyu Buddhism persisted in hybrid forms.

• Thailand & Laos: Dvaravati (Mon) states flourished in the Chao Phraya basin with moated towns and Buddhist stupas; Theravāda and Mahāyāna coexisted. Upland Lao chiefdoms maneuvered between Mon and Khmer influence.

• Cambodia (Khmer beginnings): From post-Chenla fragmentation, Jayavarman II (c. 802–835) proclaimed the Devarāja and inaugurated Angkor’s line; early capitals around Kulen–Angkor show expanding irrigation and temple programs.

• Vietnam: In 939, Ngô Quyền’s victory at Bạch Đằng ended nearly a millennium of Chinese rule, inaugurating an independent Vietnamese kingdom. South of the Red River, Champa consolidated as a Hindu-Shaiva seafaring kingdom, projecting force northward at intervals from temple-cities like Mỹ Sơn.

Insular Southeast Asia

• Sumatra (excl. Aceh & W offshore islands): Srivijaya (Palembang) reached consolidation—commanding Malacca and Sunda Straits, taxing and protecting China–India traffic, and influencing western Borneo and parts of Java. Its monasteries drew international pilgrims and linked Nalanda to Tang ports.

• Java: Sanjaya (Hindu Shaiva) and Sailendra (Buddhist) legacies framed competing courts across central/eastern Java; monumental idioms of Borobudur and Prambanan still shaped the cultural landscape; intensive rice economies underwrote dense populations and court power.

• Borneo: Coastal polities aligned with Srivijaya’s tribute circuits, exporting camphor, resins, forest products; interiors housed Dayak clan communities, loosely tied to maritime trade.

• Sulawesi: Coastal nodes in Makassar, Buton, and bays of the north acted as brokers between Java, the Philippines, and the Moluccas, honing navigational linkages that stitched the archipelago together.

• Eastern Archipelagos (Bali–Timor, Banda–Moluccas–Ceram–Halmahera, Philippines):

  • Spice Islands (Banda, Moluccas) supplied the world’s cloves and nutmeg, routed via Sulawesi and Borneo.

  • Philippines: Barangay polities (20–50 boat-household clusters) along Luzon and Visayas bays mined gold, wove textiles, and exported pearls and forest goods.

  • Bali–Timor arc balanced wet-rice, taro, and dryland farming, funneling produce into spice circuits.

Andamanasia (Srivijayan supremacy, local autonomies)

• Srivijaya at its height dominated Malacca, projecting authority into Aceh and offshore chains.

• Barus—already famed for camphor—operated under Srivijaya’s influence; Lambri remained a small coastal settlement not yet in foreign records.

• Andamanese (Onge, Jarwa, Sentinelese) maintained autonomous hunter-gatherer lifeways; Nicobar Islanders practiced Austronesian horticulture and canoe voyaging; Nias, Simeulue, Mentawai sustained fortified villages, megalithic traditions, and ritual feasting economies.

• Cocos (Keeling) and Preparis–Coco islets served as uninhabited waypoints.

Economy and Trade

• Mainland agrarian cores: expansion of wet-rice in Mekong, Chao Phraya, Red River valleys supported temple endowments and administrative elites.

• Insular thalassocracy: Srivijaya controlled strait chokepoints, taxing multi-regional traffic between India and China; Java’s rice surplus and shipyards supplied regional fleets.

• Exports: spices (clove, nutmeg), camphor and resins, gold (Philippines), tin (Malay Peninsula), rice (Java), forest and marine products.

• Redistribution hubs: Palembang, Kedah/Tambralinga, Javanese ports, Sulawesi harbors, and Philippine bays integrated inland producers with long-distance merchants.

Subsistence and Technology

• Hydraulics: Khmer and Vietnamese waterworks managed floods and extended paddy cultivation; dike–canal systems underwrote urban-temple growth.

• Naval/shipbuilding: plank-built vessels with lash-lug construction, quarter-rudders, and multi-sail rigs; harbor pilotage in straits; navigational astronomy and monsoon timing.

• Craft industries: brick temple and stone carving (Angkor, Prambanan); ceramic traditions from mainland kilns to insular polities; metalwork from Java to Champa.

• Insular subsistence: arboriculture (coconut, sago) alongside rice; reef fisheries and lagoon management sustained coastal towns.

Movement and Interaction Corridors

• Malacca Strait: Srivijaya’s toll and convoy system linked India–Arabia–East Africa with China.

• Java Sea—Makassar—Moluccas: rice and timber outbound; spices inbound; Sulawesi the cross-beam.

• Sulu–Philippine seas: gold, pearls, forest goods into Chinese and insular markets.

• Mainland river routes: Irrawaddy, Chao Phraya, Mekong, Red River channeled grain, ceramics, and ritual bronzes between interior and coast.

• Bay of Bengal stepping-stones: Nicobars, Aceh islets, and Andaman lanes as waypoints into Malacca under Srivijayan shadow.

Belief and Symbolism

• Khmer: Devarāja (divine kingship) fused Hindu sovereignty with monumental temples and linga cults.

• Mon & Pyu: Theravāda/Mahāyāna Buddhist traditions embedded in stupas and monasteries.

• Vietnam: emergence of Confucian bureaucracy alongside vital Buddhism.

• Srivijaya: Buddhist scholastic hub with Nalanda connections and Tang embassies.

• Champa: Shaiva Hindu cults in brick sanctuaries (Mỹ Sơn), merged with Austronesian ritual.

• Eastern archipelagos: robust animism and ancestor/sea-spirit cults, with Indic icons appearing in littoral shrines; Philippine ritual and barangay leadership consecrated authority through feast and exchange.

• Andamanasia: Andamanese animism of forest/sea spirits; Nias–Mentawai megalithic feasting as embodiments of mana.

Adaptation and Resilience

• Hydraulic states (Angkor, Vietnam) managed flood regimes and drought through canal–reservoir systems.

• Maritime redistribution (Srivijaya, Java, Sulawesi brokers) moved staples and luxuries to cushion local shortfalls.

• Diverse subsistence portfolios—rice, sago, root crops, arboriculture, reef fisheries—buffered climatic swings.

• Ritual–political economies (feasts, temple endowments, tribute) transformed surplus into social cohesion and diplomatic reach.

Long-Term Significance

By 963 CE, Southeast Asia crystallized as a dual structure:

• Mainland agrarian kingdoms: Khmer divine kingship taking root at Angkor; Pyu decline and Burman migrations; Mon Buddhist centers; independent Vietnam; rising Champa.

• Insular thalassocracies: Srivijaya dominating straits commerce; Java sustaining Hindu–Buddhist courts and rice armies; Borneo and Sulawesi interlaced with the spice trade; Philippine barangays ascending in gold and sea trade.

• Andamanasia: firmly within Srivijaya’s orbit at sea, yet sustaining local autonomies from the Andamans to Nias–Mentawai.

This age established Southeast Asia as the pivotal hinge of Afro-Eurasian exchange—rice empires inland, maritime federations at sea—setting the stage for Angkor’s hydraulic apogee, Pagan’s rise, Vietnamese consolidation, Cham–Khmer rivalries, and the long radiance of Srivijaya in the centuries to follow.

Southeastern Asia (820 – 963 CE): Khmer Beginnings, Pyu Decline, Cham Expansion, and Srivijaya’s Maritime Power

Geographic and Environmental Context

Southeastern Asia includes southern and eastern Myanmar, Thailand, Cambodia, Laos, Vietnam, the Malay Peninsula, Sumatra (excluding Aceh and the western offshore islands), Java, Borneo, Sulawesi, and the surrounding archipelagos (Bali–Timor, Banda, Moluccas, Ceram, Halmahera, and the Philippines).

• The Irrawaddy, Chao Phraya, Mekong, and Red River basins supported intensive wet-rice farming.

• Insular corridors — the Malacca Strait, Java Sea, Makassar Strait, Sulu Sea, and the Moluccas — connected Indian Ocean and South China Sea trade, making maritime Southeast Asia pivotal for long-distance commerce.

• Volcanic soils in Java and Sumatra produced high agricultural yields, while the Spice Islands (Moluccas, Banda) remained the world’s sole source of cloves and nutmeg.

Mainland Southeast Asia

Myanmar (southern & eastern)

• The Pyu city-states — Śrī Kṣetra, Beikthano, and Halin — were in decline after devastating raids from Nanzhao (Yunnan) in the 9th century.

• Burman-speaking groups were moving into the central Irrawaddy basin, laying groundwork for the Pagan (Bagan) polity that would rise in the next age.

• Pyu Buddhist traditions persisted, blending with new influences from India and China.

Thailand and Laos

• Dvaravati (Mon) city-states in the Chao Phraya basin flourished, building moated towns, Buddhist stupas, and shrines.

• Theravāda and Mahāyāna Buddhist traditions coexisted.

• In the uplands of Laos, smaller chiefdoms maintained shifting alliances, often under Mon and Khmer influence.

Cambodia (Khmer beginnings)

• The old polity of Chenla fragmented, giving way to ambitious rulers in the Mekong basin.

• Jayavarman II (r. c. 802–835) established the Devarāja cult, legitimizing divine kingship and founding the Angkorian line.

• Early capitals near the Kulen hills and Angkor bore evidence of expanding irrigation and temple construction.

Vietnam

• The Red River delta threw off Chinese rule when Ngô Quyền defeated Southern Han forces at the Battle of Bạch Đằng (939).

• This victory inaugurated an independent Vietnamese kingdom, ending nearly a millennium of Chinese administration.

• Central Vietnam (Champa): the Cham, Austronesian seafarers, consolidated into a Hindu-Shaiva kingdom, raising brick temples like Mỹ Sơn and expanding northward at times.

Insular Southeast Asia

Malay Peninsula

• Ports like Kedah and Tambralinga flourished as waystations for Srivijayan control of straits commerce.

• These entrepôts exchanged Indian textiles, Chinese ceramics, and Arabian goods for local resins, tin, and forest products.

Sumatra (excluding Aceh & western islands)

• Srivijaya (centered at Palembang) reached consolidation by this age, exercising naval hegemony over the Malacca and Sunda Straits.

• It drew tribute from Malay Peninsula ports and exerted influence over western Borneo and parts of Java.

• Buddhist monasteries at Palembang became international centers of learning, hosting Chinese pilgrims en route to India.

Java

• Central and eastern Java supported competing dynasties — the Sanjaya (Hindu Shaiva) and Sailendra (Buddhist).

• Monumental traditions (Borobudur, Prambanan) still influenced the cultural landscape, though major temple construction had peaked earlier.

• Java’s fertile rice fields supported dense populations and powerful courts.

Borneo

• Coastal settlements aligned with Srivijayan tribute networks, exporting camphor, resins, and forest products.

• The Dayak interior remained under shifting clan-based communities, less integrated into maritime trade.

Sulawesi

• The island developed as a maritime hub, with communities on the coasts of Makassar and Buton linking to trade routes between Java, the Philippines, and the Moluccas.

• Navigation skills here were particularly influential in connecting the archipelago.

Eastern Archipelagos (Bali–Timor, Banda, Moluccas, Ceram, Halmahera, Philippines)

• Spice Islands (Banda, Moluccas): cloves and nutmeg were harvested by local chiefdoms, traded via Sulawesi and Borneo intermediaries.

• Philippines: barangay polities (20–50 boat-based clans) clustered along bays and rivers in Luzon and Visayas. They engaged in gold mining, weaving, and sea trade, exporting gold, pearls, and forest products.

• Bali–Timor arc: mixed rice, taro, and dryland farming; local rulers tied into wider spice trade circuits.

Economy and Trade

• Mainland: wet-rice agriculture expanded in Mekong, Chao Phraya, Red River valleys.

• Insular: Srivijaya controlled straits shipping, taxing and protecting merchants between India and China.

• Spices, camphor, and resins from Moluccas, Sumatra, and Borneo moved outward.

• Gold from the Philippines, tin from the Malay Peninsula, and rice from Java entered Indian Ocean and South China Sea exchange.

Belief and Symbolism

• Khmer: Devarāja cult fused Hindu divine kingship with monumental temple building.

• Mon and Pyu: Buddhist traditions (Theravāda and Mahāyāna) persisted, expressed in stupas and monasteries.

• Vietnam: Confucian bureaucracy replaced Chinese rule, but Buddhism remained vital.

• Srivijaya: international Buddhist hub, sending embassies to Tang China and maintaining Nalanda connections.

• Champa: Shaiva Hindu cults merged with Austronesian ritual; temples served as both sanctuaries and political symbols.

• Philippines–Sulawesi–Moluccas: animist traditions of ancestor and sea spirits dominated, with imported Indic icons appearing in coastal shrines.

Adaptation and Resilience

• Hydraulic works in Angkor and Vietnam managed flood regimes and expanded farming.

• Maritime orientation in Srivijaya and the islands allowed resilience through redistribution of goods.

• Diversified economies combining rice, root crops, foraging, and trade buffered against climate shocks.

Long-Term Significance

By 963 CE, Southeastern Asia was firmly divided into:

• Mainland agrarian kingdoms: Khmer beginnings at Angkor, Pyu decline and Burman migrations, Mon Buddhist centers, independent Vietnam, rising Champa.

• Insular thalassocracies: Srivijaya commanding the straits, Java sustaining Hindu-Buddhist courts, Borneo and Sulawesi tied to spice trade.

• Eastern archipelagos: Spice Islands and Philippine chiefdoms expanding their role in long-distance commerce.

This age crystallized Southeastern Asia’s dual structure: land-based rice empires inland, and maritime federations at sea, both feeding into the great Indian Ocean–China exchange system.

Nanzhao intervenes frequently in the affairs of the principalities of the middle Mekong Valley in the later half of the eighth century, resulting in the occupation of Muang Sua in 809.

Nanzhao princes or administrators replace the aristocracy of Thai overlords.

Dates of the occupation are not known, but it probably ends well before the northward expansion of the Khmer Empire under Indravarman I (r. 877- 89) and extends as far as the territories of Sipsong Panna on the upper Mekong.

The Angkorian period lasts from the early ninth century to the early fifteenth century CE.

In terms of cultural accomplishments and political power, this is the golden age of Khmer civilization.

The great temple cities of the Angkorian region, located near the modern town of Siemreab, are a lasting monument to the greatness of Jayavarman II's successors. (Even the Khmer Rouge, who will look on most of their country's past history and traditions with hostility, will adopt a stylized Angkorian temple for the flag of Democratic Kampuchea. A similar motif is found in the flag of the PRK).

The kingdom founded by Jayavarman II also gives modern-day Cambodia, or Kampuchea, its name.

During the early ninth to the mid-fifteenth centuries, it is known as Kambuja, originally the name of an early north Indian state, from which the current forms of the name have been derived.

Jayavarman II settles north of the Tonle Sap, possibly to put distance between himself and the seaborne Javanese.

He builds several capitals before establishing one, Hariharalaya, near the site where the Angkorian complexes are built.

Indravarman I (877-89) extends Khmer control as far west as the Korat Plateau in Thailand, and he orders the construction of a huge reservoir north of the capital to provide irrigation for wet rice cultivation.

His son, Yasovarman I (889-900), builds the Eastern Baray (reservoir or tank), evidence of which remains to the present time.

Its dikes, which may be seen today, are more than six kilometers long and one point six kilometers wide.

The elaborate system of canals and reservoirs built under Indravarman I and his successors are the key to Kambuja' s prosperity for half a millennium.

By freeing cultivators from dependence on unreliable seasonal monsoons, they make possible an early "green revolution" that provides the country with large surpluses of rice.

Kambuja's decline during the thirteenth and fourteenth centuries probably is hastened by the deterioration of the irrigation system.

Attacks by Thai and other foreign peoples and the internal discord caused by dynastic rivalries divertshuman resources from the system's upkeep, and it gradually falls into disrepair.

Jayavarman II, the first king of Angkor, had declared the sovereignty of the Khmer state in 802, eventually establishing his capital at Hariharalaya near modern Siem Reap in Cambodia.

A few decades later, his successors had begun constructing Bakong in stages as the first temple mountain of sandstone at Angkor, its large brick structure elaborately ornamented and filled with stonecut images.

Located in the capital’s center and surrounded by double-walled moats, the inscription on its stele (classified K.826) says that in 881 King Indravarman I dedicated the temple to the god Shiva and consecrated its central religious image, a lingam whose name Sri Indresvara is a combination of the king's own and the suffix "-esvara", which stands for Shiva ("Iśvara").

The Bakong, with one hundred and eight tower-shrines around its central sanctuary, is his state shrine; therefore, it also houses the official Śiva's liṅga.

Although his shrines are bigger than his predecessors, they are modest compared to the later shrines.

It is also the first time in Khmer architecture where nāgas—a deity or class of entity or being, taking the form of a very great snake, specifically the king cobra, found in Hinduism, Buddhism and Jainism—are employed as guardians for the bridge between the human world and the temple, house of god.

Yasovaram, a son of King Indravarman I and his wife Indradevi becomes emperor of the Khmer in 889.

After the death of Indravarman, a succession war had been fought between his two sons, Yasovarman and his brother.

It is believed that the war was fought on land and on sea by the Tonlé Sap.

In the end, Yasovarman prevailed.

During the first year of his reign, he builds about one hundred monasteries (ashrams) throughout his kingdom.

Each ashram is used as a resting place for the ascetic and the king during his trips.

The first Yasodharapura is built around Phnom Bakheng, also referred to in inscriptions as Phnom Kandal (Central Mountain), constructed just before the foundation of the city due to Yasovarman's belief that the mountain is among the holiest of places to worship the Hindu deities.

Succeeding capitals built in the area will also be called Yasodharapura, which, when translated from the Sanskrit, conveys the meaning of "Holy City" or, by extension, "Capital City".