In the 20th century, several linguists discovered that Tsat language, within the Cham subgroup, on Hainan island in China, belongs to the Austronesian language family. Further research by those such as Thurgood (2013), Zhen yiqing (1997), and others, have exposed the relevance of the Cham subgroup to the Austronesian language family. Another geographically distant language─Acehnese, in North Sumatera, in Indonesia, has also been confirmed to be a language of the Cham subgroup, within the Austronesian set of languages (Durie 1990). Until the present, little historical comparative research has been conducted to determine the relatedness of these two languages of the same subgroup of Austronesia. Acehnese is surrounded by many other non-Cham Austronesian languages, where Tsat sits amongst of all non-Austronesian languages. We thus question whether language contact has motivated a reduction in cognate level.
For thsi study, with the aid of a Swadesh list, the core vocabularies of Tsat and Acehnese have been found. Thereforewe applied a lexicostatistics method so to find the reflections of Proto-Cham and Proto-Austronesia in Tsat and Acehnese respectively.
The findings differ surprisingly from hypotheses prior to the research. The percentage of shared cognate items of Proto-Cham in Tsat is almost the same as that in Acehnese, although the percentage of refection of Proto-Austronesian in Acehnese is much larger than that in Tsat. This indicates that both the Tsat language and Acehnese are still genetically closely related as Cham subgroup languages. Language contact has had greater impact on their degree of relatedness with the Proto-Austronesian but not on that of the Cham subgroup nature. The similar percentage of Proto-Cham reflection also suggests that they may have diverged concurrently in the history from Cham in the Southern Indo-Chine Peninsular.