Another contribution to the hypothesis for Austronesian toponyms in Vietnam

This paper employs historical phonological evidence and geographical linguistic maps to examine specific toponyms in Vietnam, including Phú Gia, Bà Đanh, Sấu - Giá, and Hà Lầm, Hà Lam, Kha Lâm, Khả Lãm, in order to further investigate the contact between Vietnamese and Austronesian speakers. Two main hypotheses have been posited regarding the origins of Austronesian toponyms, particularly those found in Northern Vietnam. The first suggests that the toponyms resulted from early contact during Austronesian migrations to Southeast Asia. The second posits that contact occurred later, possibly after the 10th century during Đại Việt's conquests of the Champa region, leading to the migration of Cham prisoners into the Northern Delta. Drawing on cultural and historical knowledge, this paper suggests Phú Gia, Bà Đanh, and Sấu - Giá likely emerged from language contact post-10th century. However, further study is needed for toponyms with Lâm/Lam/Lầm/Lãm. The findings also suggest that the presence of Austronesian-speaking residents in Northern Vietnam in antiquity is evident, though their migration timelines and directions remain debated.