The Đông Yên Châu inscription is an Old Cham inscription written in Pallava script, found in 1936 at Đông Yên Châu, northwest of Trà Kiệu, which used to be the old Champa capital known as Simhapura, in central Vietnam. The inscription was written in prose, is the oldest document of Cham (and indeed of any Austronesian language), and testifies to the existence of indigenous beliefs among the ancient Cham people of the Champa kingdom. Though not itself dated, the phrasing of the inscription is identical to those of dated Sanskrit inscriptions of Bhadravarman I of the second dynasty, who ruled Champa at the end of the 4th century CE. It contains an imprecatory formula ordering respect for the "naga of the king", undoubtedly a reference to the protective divinity of a spring or well. This vernacular text shows that in the 4th century, the land that now constitutes modern-day central Vietnam was inhabited by an Austronesian-speaking population. The evidence, both monumental and palaeographic, also suggests that Hinduism was the predominant religious system.
The fact that the language in the inscription shares some basic grammar and vocabulary with Malay has led some scholars to argue that the inscription contains the oldest specimen of Malay words in the form of Old Malay, older by three centuries than the earliest Srivijayan inscriptions from southeastern Sumatra. However, most scholars consider it established that this inscription was written in Old Cham instead. The shared basic grammar and vocabulary comes as no surprise, since Chamic and Malayic languages are closely related; both are the two subgroups of a Malayic–Chamic group within the Malayo-Polynesian branch of the Austronesian family.
