This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Chinese envoy records describe the Mekong Delta kingdom of Funan, established around the first century CE, gradually adopting Indian religious and legal custom over the centuries that followed its founding. By the fifth century the process had gone furthest under the ruler Kaundinya II, recorded as having changed all the kingdom's laws to conform to the system of India, meaning Hindu religious and administrative practice rather than a purely secular reform, and Sanskrit inscriptions from the mid fifth century survive from the kingdom as direct evidence of that adoption.
Archaeological evidence shows the Mekong Delta region was settled far earlier than Funan itself, as far back as the fourth century BCE, but that earlier settlement carries no documented connection to Hinduism. The religious history of the region begins specifically with Funan's own Indianization centuries later, a process recorded by outside observers rather than reconstructed from silence.
What this changed for Hinduism's spread was the planting of the religion's earliest documented foothold in mainland Southeast Asia, carried not by conquest but by the gradual adoption of Indian religious and legal custom into a kingdom's own governing practice. Funan's Indianization set the pattern later Khmer states would build on for centuries, including the temple building that would eventually produce Angkor Wat.