The oldest known records of a political entity in Indochina are attributed to Funan – centered in the Mekong Delta and comprising territories inside modern day Thailand.^[4] Chinese annals confirm Funan's existence as early as the first century CE. Archaeological documentation implies an extensive human settlement history since the fourth century BCE.^[5] Though regarded by Chinese authors as a single unified polity, some modern scholars suspect that Funan may have been a collection of city-states that sometimes were at war with one another and at other times constituted a political unity.^[6] From archaeological evidence, which includes Roman, Chinese, and Indian goods excavated at the ancient mercantile centre of Óc Eo in southern Vietnam, it is known that Funan must have been a powerful trading state.^[7] Excavations at Angkor Borei in southern Cambodia have likewise delivered evidence of an important settlement. Since Óc Eo was linked to a port on the coast and to Angkor Borei by a system of canals, it is possible that all of these locations together constituted the heartland of Funan.

Funan was the name given by Chinese cartographers, geographers and writers to an ancient Indianized state—or, rather a loose network of states (Mandala)^[8] — located in mainland Southeast Asia centered on the Mekong Delta that existed from the first to sixth century CE. The name is found in Chinese historical texts describing the kingdom, and the most extensive descriptions are largely based on the report of two Chinese diplomats, Kang Tai and Zhu Ying, representing the Eastern Wu dynasty who sojourned in Funan in the mid-3rd century CE.^[9]

Like the very name of the kingdom, the ethno-linguistic nature of the people is the subject of much discussion among specialists. The leading hypotheses are that the Funanese were mostly Mon–Khmer, or that they were mostly Austronesian, or that they constituted a multi-ethnic society. The available evidence is inconclusive on this issue. Michael Vickery has said that, even though identification of the language of Funan is not possible, the evidence strongly suggests that the population was Khmer.^[10]