Khmer Empire Rises
In 802 CE, according to later inscriptions, a Khmer ruler named Jayavarman II held a ceremony on Mount Kulen northeast of Angkor, proclaiming himself a universal monarch and declaring independence from Java. That date is traditionally used to mark the founding of the Khmer Empire, and the "800 AD" given here is an approximation of that moment. The state he created dominated much of mainland Southeast Asia for roughly six centuries and left behind Angkor, one of the largest pre-industrial urban complexes in the world, including Angkor Wat, often described as the largest religious monument ever built.
Before this, the region was home to a number of smaller kingdoms, collectively known to Chinese sources as Funan and Chenla. Funan, centered on the Mekong Delta, flourished through maritime trade between India and China and absorbed Indian religious and political ideas, including Sanskrit, Hindu cults, and Buddhist practice. Chenla, its successor in the 6th to 8th centuries, appears to have been fragmented into rival polities. Jayavarman II, who may have spent time at a court in Java or the Malay world, is credited with unifying these competing Khmer lands, though much of what we know comes from inscriptions written generations later, so the details of his life remain uncertain.
His key innovation was ideological. Drawing on Hindu traditions, he promoted the cult of the "devaraja," usually interpreted as a god-king or a royal deity, which tied the ruler's authority to divine sanction. Historians debate exactly what this cult meant in practice. Later kings built on this foundation, moving the capital to the Angkor area near the Tonlé Sap, Southeast Asia's great freshwater lake. There they developed an elaborate system of reservoirs, canals, and rice fields that supported a large population and a powerful state.
The empire reached its height in the 12th and early 13th centuries. Suryavarman II built Angkor Wat in the early 1100s as a Hindu temple dedicated to Vishnu. Jayavarman VII, a Buddhist king who reigned later in that century, constructed the walled city of Angkor Thom and its enigmatic Bayon temple with its massive carved faces, and expanded the empire's reach across much of present-day Cambodia, Thailand, Laos, and southern Vietnam.
Angkor's decline was gradual and had multiple causes. Historians point to pressure from the rising Thai kingdom of Ayutthaya, shifts in trade routes, religious change toward Theravada Buddhism, and climate stresses such as severe droughts and floods that strained the water system. The Thai sack of Angkor in 1431 is often cited as a turning point, after which the Khmer court moved south. Angkor itself was never entirely abandoned, and Angkor Wat remained a place of worship. Today it appears on Cambodia's national flag and is a UNESCO World Heritage Site.