The early inhabitants of Langkasuka were probably an eclectic assemblage of early Malays, Mons and Khmers. The maritime nature of the polity alludes to Austronesian (the greater Malay group) dominance. Significant Sumatran Malay acculturation commenced with the Sri Vijayan conquest of the Kra Isthmus in the 8th century. The Langkasukans were certainly not T’ais. At that time, the ancestral T’ais were still in the hills and river valleys of Yunnan prior to being displaced to Indo-China by the Han Chinese. Linguistically, Sri Vijayan rule, which flourished in the 9th and 11-13th centuries, signified the gradual eradication of Austro Asiatic languages (including Mon-Khmer) and early Austronesian tongues by High Malay, Sri Vijaya’s language of administration. By the 13th century, Malay language, culture and identity had subsumed other populations of the peninsula’s northern half up to the Kra Isthmus. The last vestiges of the old Mon-Khmer language are today found in the native vernacular of the aborigines of Malaya and south Thailand, the so-called Aslian Group.
The coming of Islam further cemented the affiliation of the Isthmian Malays to the people of the Nusantara. However, the arts and culture of the Patani-Kelantan region (historically, extending northwards up to present-day Phatthalung) till this day carry a distinct flavour of Khmer courts of old, exemplified by Wayang Kulit, Mak Yong, Menora and Petri (respectively, traditional shadow play depicting adapted Ramayana-Mahabhrata epics; a royal court theatre combining dance, opera, drama and comedy; a complex rhythmic dance drama depicting ancient pre-Islamic folklore; and the cryptic musical-dance spiritual cleansing ritual), all often inaccurately attributed to a “Thai” or “Siamese” origin. The T’ai (or Thai) themselves adopted and emulated these high culture from the courts of Cambodia when they rebelled against their Khmer rulers in the 13th century and formed their ancestral polities in the central Chao Phraya basin. See Geoffrey Benjamin’s “Ethnohistorical Perspectives on Kelantan’s Prehistory” in Kelantan Zaman Awal, 1987, pp.108-46, for a fascinating discourse on the linguistic-cultural evolution of the northern peninsula Malays, particularly the Patani-Kelantanese group. His hypothesis somewhat reaffirmed the socio-cultural specificities of the Patani-Kelantan Malays and their intrinsic distinction from other Malays of the peninsula.