Here is Australia, almost every Aboriginal tribe has their own dialect. Often times tribes that lived only a few hundred miles apart had their own unique language. Not surprising that the article mentions there are over 7000 different languages spoken on this planet.
Austoasiatic² is the family that includes Vietnamese and Khmer, but not Malay.
2: AKA Mon-Khmer https://en.wikipedia.org/wiki/Austroasiatic_languages