I understand Thai and Lao and all their dialects, and Vietnamese and all its dialects to be of totally different language evolutionary families (Tai Kra-Dai and Astroasiatic).
I can speak and read some basic Thai and have visited Vietnam and my opinion is that both languages are very different;
When I just started to learn about them they sounded to me extremely similar but with time extremely different.
But I am not sure it is correct to say that there aren't any significant commonalities at all:
- Both are significantly tonal
- I am impressed that both have lots of B, T and L.
- I think that both languages have large usage of consonant-vowel combinations
- I am impressed that both share, humbly, to my ear, very similar yet not identical quite unique phonemes, such as:
Sound comparison 1: Both share the rare
ng consonant (
ง in Thai) | available in Nguyễn in Vietnamese
Sound comparison 2:
◌ู in Thai for uu sound | m(
ườ)i for a similar uu sound in Vietnamese
Sound comparison 3:
เออ in Thai for an impolite agreement between close friends only | A similar way to agree impolitely(?) in Vietnamese (as far as I have recognized)
Sound comparison 4:
มื in Thai for m(
ue') sound | Shouldn't it be similar to, for example, the
ue' in Tú Xương?
Sound comparison 5: The Issan (Thai-Lao) way to pronounce the word Eighty | A similar way in Vietnamese (as far as I have recognized)
When I learn of Issan (the geographically closer part of Thailand to Vietnam) architecture, furniture, musical instruments, traditional food and clothing I do start to think that common effects might were more common than it may seem. Issan Language itself might be closer.
Using a metaphor I would say that these are two different buildings from the same materials (same proto language perhaps? "proto south east asian" perhaps.
Is there a theory aimed to doubt the common strict distinction between Thai and Vietnamese showing that Proto Tai Kra Dai might have been effected from Vietnamese or vice versa, more than commonly thought?