International trade brought South Asian Hindu and Buddhist traditions to mainland Southeast Asia. This economic foundation allowed new political states to form in the Mekong Delta area, which were led by rulers who presented themselves as god-kings (devarajas). The pre-Angkor kings claimed to be incarnations of Shiva or Vishnu, and their names reflect this affiliation. Their authority is also based on South Asian chakravartin (universal king) concepts of rulership that came to Southeast Asia in the form of Sanskrit texts. The Mekong River supported canal and irrigation systems that in turn led to a long period of agricultural prosperity; moreover, this river functioned as a highway supplying trade goods and raw materials from the interior to international maritime trade networks linked to China, Java, and South Asia. This maritime trade system provided an alternative to the overland trade network that connected India and China via the Central Asian Silk Road.

Our most complete accounts of the pre-Angkorian kingdoms come from Chinese records; the earliest of these kingdoms was Funan in the Mekong Delta area. By the early sixth century, Chinese sources tell of multi-armed (Hindu) deities being venerated, and mention missions to China from named kings. In the seventh century, Funan was in decline and the state of Zhenla emerged in the northern Mekong Delta. Archaeological remains of cities, temples, isolated sites, and images allow for a clearer understanding of political centers even if these sites are difficult to relate to the states mentioned in the Chinese sources. The city of Angkor Borei was established in the early centuries of the Common Era and by the third century had become a regional capital of Funan in the area of the Mekong Delta. By the late sixth century, rulers and other wealthy patrons from this rich trading center began to sponsor the production of Buddhist Theravadin and Mahayana images (1980.526.3). An early and rare monumental image of the Buddha (2005.512) relates to the production of large-scale Buddhist imagery that began to appear across South Asia. Such monumental Buddhas occur from Bamiyan in Afghanistan to Ajanta in western India.

The establishment of Hindu temple complexes was widespread in this early period, an important center being the site of Prasat Andet. In the seventh and eighth centuries, a cult surrounding the veneration of a composite of Vishnu (Hari) and Shiva (Hara) was popular in the Mekong Delta area (1977.241). Most popular of all were images of Shiva (1987.17) and his nonanthropomorphic representation as a linga (1994.510). Shiva was also depicted as half male and half female (1993.387.4) to indicate the relationship of the unified whole; the conceptual male half is given a manifest existence through the active female presence (prakrti). Also important was Ganesha (1982.220.7), who is the Hindu elephant-headed son of Shiva and Parvati. As a deity who removes obstacles, Ganesha is a god of success; in this sense, he is a deity that has great importance in terms of everyday existence. He was venerated before turning to other gods, thus removing potential obstacles between the worshipper and the divine. In Southeast Asia, Ganesha had a more independent status than in India; his images were often housed in separate temples as primary icons of worship.

The early artistic heritage of peninsular Thailand is related to the pre-Angkorian tradition. Lingas (1992.150.3) attest to the popularity of the Hindu god Shiva, though many Buddhist images have also been found, such as a standing Avalokiteshvara (1982.64). A number of small kingdoms likely flourished on the peninsula. The later artistic heritage in this area shows close affinities to the enigmatic kingdom of Shrivijaya, which was probably centered in Sumatra.

It is remarkable that the body of pre-Angkorian sculpture known from numerous sites in southern Cambodia and Vietnam as well as peninsular Thailand shows an overall stylistic coherence. Although this extraordinarily brilliant material has clear affinities with South Asian Pallava, Andhran (28.105), and Gupta (1979.6) production, in many ways it reflects an artistic vocabulary that has been transformed into a purely Southeast Asian idiom. The ovoid facial features of Gupta sculpture have been replaced with a different physiognomy; the figures are more austere in expression and more naturalistic. Today these regions are mostly Buddhist, but in the seventh and eighth centuries both Hinduism and Buddhism, as well as concepts of asceticism, engaged these new Southeast Asian patrons. Although the links to Indian artistic traditions are clear, even the earliest Pre-Angkorian sculpture is distinctly Southeast Asian in style. Remarkably, some wood images have been found, raising the possibility that works in more perishable materials preceded stone icons.