The "native" or "pre-Austroasiatic" layer corresponds to the independent language phylum that was spoken by the hunter-gatherers of the Dingsishan culture in Guangxi during the Early Neolithic.
Various Austroasiatic words have no parallels in neighboring phyla, such as: fire, hand, ear, stone, moon, bird, I, etc.
Vovin (1993), in his Proto-Ainu book, notes some similarities between Proto-Ainu and Austroasiatic, but I do not consider those to be especially convincing. Some proponents may argue that pre-Ainu and pre-Austroasiatic shared a common ancestor (or rather an ancient shared component) due to an ancient migration of Sundadonts up the coast of eastern Asia during Paleolithic times. However, this is beyond the linguistic horizon for reconstructable language phyla.