The closely related Mon and Khmer peoples entered Southeast Asia along migration routes from southern China in the ninth century B.C. The Khmer settled in the Mekong River Valley, while the Mon occupied the central plain and northern highlands of modern Thailand and large parts of Burma. Taking advantage of Funan’s decline in the sixth century A.D., the Mon began to establish independent kingdoms, among them Dvaravati in the northern part of the area formerly controlled by Funan and farther north at Haripunjaya. Meanwhile the Khmer laid the foundation for their great empire of the ninth to fifteenth centuries A.D. This empire would be centered at Angkor (near modern Siem Reap) in Cambodia.
The Mon were receptive to the art and literature of India, and for centuries they were the agents for diffusing Hindu cultural values in the region. The frequent occurrence of Sanskrit place-names in modern Thailand is one result of the long and pervasive Indian influence.
In the eighth century, missionaries from Ceylon (present-day Sri Lanka) introduced the Mon to Theravada Buddhism. The Mon embraced Buddhism enthusiastically and conveyed it to the Khmer and the Malay of Tambralinga (see Religion , ch. 2). The two Indian religious systems--Hindu and Buddhist--existed side by side without conflict. Hinduism continued to provide the cultural setting in which Buddhist religious values and ethical standards were articulated. Although Buddhism was the official religion of the Mon and the Khmer, in popular practice it incorporated many local cults.
In spite of cultural dominance in the region, the Mon were repeatedly subdued by their Burmese and Khmer neighbors. In the tenth century Dvaravati and the whole of the Chao Phraya Valley came under the control of Angkor. The Khmer maintained the HinduBuddhist culture received from the Mon but placed added emphasis on the Hindu concept of sacred kingship. The history of Angkor can be read in the magnificent structures built to glorify its monarchy. Ultimately, however, obsession with palaces and temples led the Khmer rulers to divert too much manpower to their construction and to neglect the elaborate agricultural system-- part of Angkor’s heritage from Funan--that was the empire’s most important economic asset.