Proto-Tai is thereconstructedproto-language (common ancestor) of all theTai languages, including modernLao,Shan,Tai Lü,Tai Dam,Ahom,Northern Thai,Standard Thai,Bouyei, andZhuang. The Proto-Tai language is not directly attested by any surviving texts, but has beenreconstructed using thecomparative method.

It was reconstructed in 1977 byLi Fang-Kuei^[1] and by Pittayawat Pittayaporn in 2009.^[2][3]

The following table shows the consonants of Proto-Tai according toLi Fang-Kuei'sA Handbook of Comparative Tai (1977), considered the standard reference in the field. Li does not indicate the exact quality of the consonants denoted here as [tɕ,tɕʰ anddʑ], which are indicated in his work as [č, čh, ž] and described merely aspalatalaffricate consonants.

The table below lists the consonantal phonemes of Pittayawat Pittayaporn's reconstruction of Proto-Tai.^{[2]: p. 70} Some of the differences are simply different interpretations of Li's consonants: the palatal consonants are interpreted as stops, rather than affricates, and the glottalized consonants are described using symbols forimplosive consonants. However, Pittayaporn's Proto-Tai reconstruction has a number of real differences from Li:

1. Pittayaporn does not allow foraspirated consonants, which he reconstructs as secondary developments inSouthwestern Tai languages (after Proto-Tai split up into different languages).
2. He also reconstructs a contrastive series ofuvular consonants, namely */q/, */ɢ/, and */χ/. No modern dialect preserves a distinct series of uvular consonants. Pittayaporn's reconstruction of the sounds is based on irregular correspondences in differing modern Tai dialects among the sounds /kʰ/, /x/ and /h/, in particular in thePhuan language and theKapong dialect of thePhu Thai language. The distinction between /kʰ/ and /x/ can be reconstructed from theTai Dón language. However, words with /x/ in Tai Dón show three different types of correspondences in Phuan and Kapong Phu Thai: some have /kʰ/ in both languages, some have /h/ in both, and some have /kʰ/ in Phuan but /h/ in Kapong Phu Thai. Pittayaporn reconstructs the correspondence classes as reflecting Proto-Tai /x/,/χ/ and /q/, respectively.^[4]

There is a total of 33–36 consonants, 10–11 consonantalsyllable codas and 25–26 tautosyllabic consonant clusters.

Tai languages have many fewer possible consonants in coda position than in initial position. Li (and most other researchers) construct a Proto-Tai coda inventory that is identical with the system in modern Thai.

Pittayaporn's Proto-Tai reconstructed consonantal syllable codas also include *-l, *-c, and possibly *-ɲ, which are not included in most prior reconstructions of Proto-Tai.^{[2]: p. 193} Below is the consonantal syllabic coda inventory:

Norquest (2021) reconstructs thevoiceless retroflex stop /ʈ/ for Proto-Tai. Examples of voiceless retroflex stops in Proto-Tai:^[5]

Norquest (2021) also reconstructs a series ofbreathy voiced initials (*bʱ, *dʱ, *ɡʱ, *ɢʱ) for Proto-Tai. Examples of breathy voiced initials in Proto-Tai:^[5]

Some sound correspondences among Proto-Tai, Proto-Northern Tai, and Proto-Southern Tai (i.e., the ancestor of the Central and Southwestern Tai languages) uvular initials given in Ostapirat (2023) are as follows.^[6]

Initial velar correspondences, on the other hand, are identical.^[6]

Li (1977) reconstructs the following initial clusters:

Pittayaporn (2009) reconstructs two types of complexonsets for Proto-Tai:

1. Tautosyllabic clusters – considered one syllable.
2. Sesquisyllabic clusters – "one-and-a-half" syllables. ("Sesquisyllabic" is a term coined byJames Matisoff.) However, sesquisyllabic clusters are not attested in any modern Tai language.

Tautosyllabic consonant clusters from Pittayaporn^{[2]: p. 139} are given below, some of which have the medials *-r-, *-l-, and *-w-.

Pittayaporn's Proto-Tai reconstruction also hassesquisyllabic consonant clusters.Michel Ferlus (1990) had also previously proposed sesquisyllables forProto-Thai-Yay.^[7] The largerTai-Kadai family is reconstructed with disyllabic words that ultimately collapsed to monosyllabic words in the modern Tai languages. However, irregular correspondences among certain words (especially in the minority non-Southwestern-Tai languages) suggest to Pittayaporn that Proto-Tai had only reached the sesquisyllabic stage (with a main monosyllable and optional precedingminor syllable). The subsequent reduction to monosyllables occurred independently in different branches, with the resulting apparent irregularities in synchronic languages reflecting Proto-Tai sesquisyllables.

Examples of sesquisyllables include:

Other clusters include *r.t-, *t.h-, *q.s-, *m.p-, *s.c-, *z.ɟ-, *g.r-, *m.n-; *gm̩.r-, *ɟm̩ .r-, *c.pl-, *g.lw-; etc.

Below are Proto-Tai vowels from Pittayaporn.^{[2]: p. 192} Unlike Li's system, Pittayaporn's system has vowel length contrast. There is a total of 7 vowels with length contrast and 5diphthongs.

Thediphthongs from Pittayaporn (2009) are:

• Rising: */iə/, */ɯə/, */uə/
• Falling: */ɤɰ/, */aɰ/

Proto-Tai had three contrasting tones on syllables ending withsonorant finals ("live syllables"), and no tone contrast on syllables withobstruent finals ("dead syllables"). This is very similar to the situation inMiddle Chinese. For convenience in tracking historical outcomes, Proto-Tai is usually described as having four tones, namely *A, *B, *C, and *D, where *D is a non-phonemic tone automatically assumed by all dead syllables. These tones can be further split into a voiceless (*A1 [1], *B1 [3], *C1 [5], *D1 [7]) and voiced (*A2 [2], *B2 [4], *C2 [6], *D2 [8]) series. The *D tone can also be split into the *DS (short vowel) and *DL (long vowel) tones. With voicing contrast, these would be *DS1 [7], *DS2 [8], *DL1 [9], and *DL2 [10].^[4][8] OtherKra–Dai languages are transcribed with analogous conventions.

The following table of the phonetic characteristics of Proto-Tai tones was adapted from Pittayaporn.^{[2]: p. 271} Note that *B and *D are phonetically similar.

Proto-Tai tones take on various tone values and contours in modernTai languages. These tonal splits are determined by the following conditions:

1. "Friction sounds": Aspirated onset, voiceless fricative, voiceless sonorant
2. Unaspirated onset (voiceless)
3. Glottalized/implosive onset (voiceless)
4. Voiced onset (voiceless)

In addition,William J. Gedney developed a "tone-box" method to help determine historical tonal splits and mergers in modern Tai languages. There is a total of 20 possible slots in what is known as theGedney's Tone Box.^{[9][10][11][12]}

Proto-Tai tones correspond regularly toMiddle Chinese tones.^[13][14] (Note thatOld Chinese did not have tones.) The following tonal correspondences are from Luo (2008). Note that Proto-Tai tone *B corresponds to Middle Chinese tone C, and vice versa.

Gedney (1972) also included a list of diagnostic words to determine tonal values, splits, and mergers for particular Tai languages. At least three diagnostic words are needed for each cell of the Gedney Box. The diagnostic words preceding the semicolons are from Gedney (1972), and the ones following the semicolons are from Somsonge (2012)^[15] and Jackson,et al. (2012).^[16] StandardThai (Siamese) words are given below, withitalicised transliterations.

Note that the diagnostic words listed above cannot all be used for other Tai-Kadai branches such asKam–Sui, since tones in other branches may differ. The table below illustrates these differences among Tai and Kam–Suietyma.

In 2007, Peter K. Norquest undertook a preliminary reconstruction of Proto-Southern Kra-Dai, which is ancestral to theHlai languages,Ong Be language, andTai languages.^[17] There are 28 consonants, 5–7 vowels, 9 closed rimes (not including vowel length), and at least 1diphthong, *ɯa(C).

Proto-Southern Kra-Dai medial consonants also include:

• *C^(V)-m
• *C^(V)-n
• *C^(V)-ɲ
• *C^(V)-ŋ
• *C^(V)(i)l
• *C(u)r
• *p(i)l
• *k-l

Proto-Southern Kra-Dai also includes thediphthong *ɯa(C).

Unlike its modern-day monosyllabic descendants, Proto-Tai was asesquisyllabic language (Pittayaporn 2009). Below are some possible Proto-Tai syllable shapes from Pittayaporn.^{[2]: p. 64}

Legend:

• C = consonant
• V = vowel
• (:) = optional vowel length
• ^T = tone

During the evolution from Proto-Tai to modern Tai languages, monosyllabification involved a series of five steps.^{[2]: p. 181}

1. Weakening (segment becomes less "consonant-like")
2. Implosivization
3. Metathesis
4. Assimilation
5. Simplification (syllable drops at least one constituent)

This sectionneeds expansion. You can help byadding missing information.(November 2014)

Robert M. W. Dixon (1998) suggests that the Proto-Tai language wasfusional in itsmorphology because of related sets of words among the language's descendants that appear to be related throughablaut.^[18]

Proto-Tai had a SVO (subject–verb–object) word order likeChinese and almost all modernTai languages. Its syntax was heavily influenced by Chinese.

Examples of Kra-Hlai-Tai isoglosses as identified by Norquest (2021):^[5]

Examples of Hlai-Be-Tai isoglosses as identified by Norquest (2021):^[5]

Examples of Be-Tai isoglosses as identified by Norquest (2021):^[5]

Ostapirat (2023) notes that as inProto-Hmong–Mien, prenasalized consonant initials in Proto-Tai often correspond with prenasalized consonant initials inOld Chinese (with the Old Chinese reconstructions below from Baxter & Sagart 2014^[19]).^[6]

• List of Proto-Tai reconstructions (Wiktionary)
• Proto-Kra language
• Proto-Hlai language
• Proto-Austronesian language
• Austro-Tai languages

Notes

Sources

• ABVD: Proto-Tai word list
• ABVD: Proto-Southwestern Tai word list
• ABVD: word lists of Kra-Dai languagesArchived 31 October 2020 at theWayback Machine

Dictionaries

• Database query to Tai–Kadai etymology
• Thai Lexicography Resources

• Tai languages
• Proto-languages

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