Proto-Kra–Dai language

Proto-Kra–Dai (typically abbreviated as PKD) is the proposed reconstructed ancestor of the Kra–Dai languages.

Background
No full reconstruction of Proto-Kra–Dai has been published to date, although tentative reconstructions of many Proto-Kra–Dai roots have been attempted from time to time. Some preliminary Proto-Kra–Dai forms have been reconstructed by Benedict (1975) and Wu (2002). Wu (2002) presents a reconstruction of Proto-Kra–Dai phonemes, which is based on data from the Tai, Kam-Sui, Hlai, and Kra branches.

Liang & Zhang (1996) propose a reconstruction of Proto-Kra–Dai (原始侗台语) initials and finals, using data from all Kra–Dai branches except for Kra and Jiamao.

Phonology
Proto-Kra–Dai has the finals *-l and *-c, which have been lost in most present-day Kra–Dai languages. It also has the final stops *-p, *-t, *-k and final nasals *-m, *-n, *-ŋ.

Ostapirat (2023) proposes the following consonant inventory for Proto-Kra–Dai, which is relatively simple compared to that of Proto-Tai and other lower-level reconstructions.

Norquest (2020) proposes the preglottalized sonorants *ʔb, *ʔd, *ʔɖ, *ʔɟ for Proto-Kra–Dai, as part of a four-way phonation distinction in Kra-Dai sonorants consisting of preaspirated, voiceless, plain, and preglottalized sonorants. Norquest (2020) also reconstructs velarized initial consonants (*Cˠ-) in Proto-Kra–Dai.

Below is a table of Proto-Kra–Dai pre-syllables and their developments as proposed by Norquest (2020).

Ostapirat (2023) considers many Proto-Tai spirants and rhotics to have developed from the intervocalic lenition of Proto-Kra–Dai medial obstruents. Voicing in the Proto-Tai initial is determined by the voicing of the preceding consonant in the Proto-Kra–Dai form.

Some Proto-Kra–Dai sesquisyllabic consonant onsets reconstructed by Ostapirat (2023) are:

Liang & Zhang (1996)
Liang & Zhang (1996) propose the following reconstructions of Proto-Kra–Dai (原始侗台语) initials and finals, using data from all Kra–Dai branches except for Kra and Jiamao.


 * Initial consonants
 * Plain stop initials
 * *p, *pw, *pl, *plw, *pr
 * *t, *tl, *tr
 * *k, *kw, *kl, *klw, *kr, *krw
 * *q, *ql, *qr, *ʔ
 * *b, *bw, *bl, *blw, *br
 * *d, *dl, *dr
 * *g, *gw, *gl, *glw, *gr, *grw, *ɢ
 * Voiced aspirated initials
 * *bɦ, *bwɦ, *brɦ
 * *dɦ, *ndlɦ
 * *gɦ, *gwɦ
 * *ɣɦ, *ɣwɦ, *ɢɦ, *ʁɦ, *sɢrɦ
 * Preglottalized initials
 * *ʔb, *ʔbw, *ʔbl, *ʔblw
 * *ʔd, *ʔdl, *ʔdr
 * *ʔm, *ʔml, *ʔmr
 * *ʔn, *ʔnl, *ʔnr, *ʔȵ, *ʔŋ, *ʔŋw
 * Voiceless nasal initials
 * *m̥, *m̥w, *m̥l, *m̥r, *m̥rw
 * *n̥, *n̥l, *ȵ̥, *ȵ̥w, *ŋ̥, *ŋ̥w
 * Plain nasal initials
 * *m, *mw, *ml, *mr
 * *n, *nr, *ȵ, *ŋ, *ŋw, *ŋr, *ɴl
 * Prenasalized initials
 * *mp, *mpl, *mpr
 * *nt, *ntl, *ntr
 * *ŋk, *ŋkw, *ŋkl
 * *mb, *mbl, *mbr
 * *nd, *ndl, *ndr
 * *ŋg, *ŋgl, *ŋgr
 * Glide and liquid initials
 * *ʔw, *ʔr, *ʔj
 * *w̥, *l̥, *r̥, *j̥
 * *w, *l, *r, *j
 * Fricative initials
 * *s, *sw, *sl, *sr, *ɕ, *x, *xw, *xl, *xr, *h
 * *z, *zl, *zr, *ʑ, *ɣ, *ɣw, *ɣl, *ʁ, *ɦ
 * Initial clusters beginning with fricatives
 * *xp, *xpl, *xpr, *xt, *xk, *xkw, *xkl, *xklw, *xkr, *xkrw, *xq, *xql
 * *sp, *spw, *spl, *st, *stl, *str, *sk, *skw, *skl, *skr, *skrw, *sq, *sqr
 * *zb, *zd, *zdw, *zgr


 * Vowels and diphthongs
 * *a, *a, *i̯a, *u̯a, *ɯ̯a
 * *ə̯, *i̯ə, *u̯ə
 * *ɛ, *i̯ɛ, *e, *i̯e
 * *ɔ, *u̯ɔ, *ɯ̯ɔ, *o, *i̯o, *u̯o, *ɯ̯o
 * *i̯, *u̯i, *ie ,iə, *ia, *iɛ
 * *u, *i̯u, *ɯ̯u, *ue, *uə, *ua, *uo, *uɔ, *uɯ
 * *ɯ, *ɯe, *ɯə, *ɯa, *ɯɔ, *ɯu

Ostapirat (2018, 2023)
Weera Ostapirat (2018a) reconstructs disyllabic forms for Proto-Kra–Dai, rather than sesquisyllabic or purely monosyllabic forms. His Proto-Kra–Dai reconstructions also contains the finals and. Ostapirat (2018b:113) lists the following of his own Proto-Kra–Dai reconstructions.

Notes:
 * : either or
 * : unspecified consonant
 * and are distinct from  and.

Some additional tentative Proto-Kra–Dai reconstructions by Ostapirat (2023) include the following.

Norquest (2020)
Norquest (2020) lists the following of his own Proto-Kra–Dai and other lower-level reconstructions.

Lower-level reconstructions
Norquest (2021) provides the following lower-level reconstructions for each branch of Kra–Dai.

Note that like Jiamao, Proto-Be does not distinguish between tone categories B and C, but rather only has an X category, which Chen (2018) names as tone category BC.