The Sa Huynh culture, which spread over Central Vietnam during the early Metal Age, is generally associated with an Austronesian-speaking (Chamic) population. Solheim advocated the close similarity between pottery found at the Kalanay Cave in Masbate, Central Philippines, and the Sa Huynh culture in Central Vietnam. However, based on our recent archaeological research, Kalanay-type pottery is actually a feature of the jar burials at the Hoa Diem site that probably postdates Sa Huynh cultural sites. Solheim also found strikingly similar pottery from Samui Island in Southern Thailand that is quite different from Sa Huynh. The absence of a specific type of earring called lingling-o at Hoa Diem and Kalanay also suggests a chronological gap from the Sa Huynh culture. A bio-anthropological analysis of the Hoa Diem skeletons is consistent with a close affinity to insular Southeast Asians, suggesting long-distance cultural interaction and/or the demographic movement of Austronesian speakers across the South China Sea in the 1st and 2nd centuries AD.
"The type site at Liangzhu was discovered in Yuhang County, Zhejiang and initially excavated by Shi Xingeng in 1936. A 2007 analysis of the DNA recovered from human remains shows high frequencies of Haplogroup O1 in Liangzhu culture linking this culture to modern Austronesian and Tai-Kadai populations. It is believed that the Liangzhu culture or other associated subtraditions are the ancestral homeland of Austronesian speakers."
SapphireSky gave the source that proves Austronesians and Vietnamese has a same ancestor