Geographical distribution of proto-Tai

The origin and the geographical distribution of proto-Tai have long been a hot debate among scholars specialized in Southeast Asian linguistics and sinology. The present-day Tai-Kadai linguistic stock does not occupy the coastal area of mainland China, however, there is evidence for very ancient Tai substrata in Han dialects spoken in south China coast. In all of the southern Chinese dialects there are many colloquial words that are never written down and for which, in fact, no written graphs exist. They represent various linguistic layers, including the oldest, non-Sinitic substrata. Before the arrival of the ethnic Han immigrants to south China during the Han dynasties (206 B.C-A.D. 220), the southern China was occupied by peoples who are thought to speak proto-Daic language. It is possible that Wu, Min, and Cantonese originated through the mixing of an early form of Old Southern Chinese with an early form of Tai. Contemporary scholars agreed that after the arrival of the ancient Chinese in South China, Daic speakers who remained near the coast were eventually absorbed by the Chinese. According to some records of ancient Yue language, including Yueren Ge (越人歌), Weijialing (维甲令), and Yuejueshu (越绝书), the ancient Yue language scattered throughout ancient South China was in fact spoken by the ancestors of Kam-Tai people. The situation was unchanged until the destruction of the Yue kingdom by the Chu kingdom. After that, the ancient Chu language was gradually replaced by the ancient Yue language that became the basis of several modern southern Chinese dialects. In 1996, Robert Bauer presented a lexical comparison between Cantonese and Tai-Kadai languages as follows:

Gloss	Cantonese (IPA)	Tai-Kadai (IPA)
young chicken which has not laid eggs	kɐj1 hɔ:ŋ2	kai5 ha:ŋ6 Zhuang-Wuming
to step on, tread (1)	ja:ŋ5	jâ:ŋ Thai
to step on, tread (2)	njɐm5	ɲam Lao
to wink, blink (1)	tsa:p7b	dʑɑp7 Buyi
to wink, blink (1)	jɐp7	jɑp7 Dong
excrement	kʰɛ:1	kʰî:7 Thai
to cover (1)	kʰɐm3	kʰɔ:m6 Li-Quandui
to cover (2)	kʰɐp7a	kʰop7 Li-Tongshi
to cover (3)	kɛm3	kəm5a Dong
to cover (4)	kɐp7a	kəp8 Maonan
to cover (5)	kʰiam3	kʰlu:m2 Thai
to press down	kɐm6	kam6 Buyi
frog	kɐp7b na:3	kòp Thai
to bite	kʰɐp8	kʰòp Thai
pen, coop	lok8	kʰɔ̂:k Thai
to scald, boil, burn	lok8	luâk Thai
to collapse, topple, fall down (bldg.)	lɐm5	lóm Thai
to step across	la:m5	ɲa:m2 Li-Xifang
to slip off, come off	lɐt7a	lùt Thai

Bauer noted that the distinction between long and short vowels found in the Yue dialects sets them apart from all other Han dialect groups which do not make use of differences in vowel length. The Tai languages also distinguish between long and short vowels but do so on an even larger scale than is found in Cantonese. In the early 1980s, a Zhuang linguist by the name of Wei Qingwen electrified the scholarly community in Guangxi by using reconstructed Old Chinese to identify the language of the 越人歌 or Yueren Ge 'Song of the Yue Boatman' as a language ancestral to Zhuang. This song is found in the 善说 Shanshuo chapter of the Shuoyuan 说苑 or ‘Garden of Persuasions’. Its lyrics was recorded phonetically in which a Chinese character is used to transcribe a syllable in the non-Chinese language of the song. It is important to mention that this song tells the story of Zhuang Xin 莊莘 (some say dating from 528 BC, based upon reports of when the personages involved in this story lived). Zhuang Xin was an official of the Chu Kingdom 楚国, who by chance glimpsed a prince 襄成 Xiang Cheng with retainers on a dock waiting to cross a river. He hurried to pay his respects and was rebuffed by the nobleman when he offered his hand. He washed and returned, saying that his Lordship must know the story of a certain Marquis E 鄂 who, some time before, was so warmly greeted by a boatman, with oars lofted singing a paean to honor his distinguished client.

Map of the Warring States period (5th century BC)

The Marquis could not understand the Yue language so he requested that the song lyrics be translated into the Chu language and was so moved by the words he shook out his sleeves and covered the boatman in his cloak. Zhuang noted that he, as an official, was not as lowly in status as the boatman; and the Prince, was not as elevated in office as the Marquis, and thus they should not disrespect one another. The Prince chastened by these words apologized. In 1991, Zhengzhang Shangfang followed Wei’s insight but used Thai script for comparison. Thai was chosen because it retains an archaic spelling system and has been documented in written records since the late 13th century. Zhengzhang Shangfang's interpretation is given below with Thai script, Chinese script and Chinese glosses being omitted.

Old Chinese	ɦgraams	ɦee	brons	tshuuʔ	ɦgraams
Historical Thai phonetic values	glamx	ɦee	blɤɤn	cɤɤ, cɤʔ	glamx
English glosses	evening	ptl.	joyful	to meet	evening
Zhengzhang's English translation	Oh, the fine night, we meet in happiness tonight!

Old Chinese	la	thjang<khliang	gaah	draag	la	thjang	tju<klju
Historical Thai phonetic values	raa	diaangh	kraʔ-	ʔdaak	raa	djaangh	cɛɛu
English glosses	We, I	be apt to	shy, ashamed		We, I	be good at	to row
Zhengzhang's English translation	I am so shy, ah! I am good at rowing.

Old Chinese	tju	khaamʔ	tju	jen	ɦaa	dzin	sa
Historical Thai phonetic values	cɛɛu	khaamx	cɛɛu	jɤɤnh	ɦaa	djɯɯnh	saʔ
English glosses	to row	to cross	to row	slowly	ptl.	joyful	satisfy, please
Zhengzhang's English translation	Rowing slowly across the river, ah! I am so pleased

Old Chinese	moons	la	ɦaa	tjau<kljau	daans	dzin	lo
Historical Thai phonetic values	mɔɔn	raa	ɦaa	caux	daanh	djin	ruux
English glosses	dirty, ragged	we, I	ptl.	prince	Your Excellency	acquainted	know
Zhengzhang's English translation	Dirty though I am, ah! I made acquaintance with your highness the Prince.

Old Chinese	srɯms	djeʔ<gljeʔ	sɦloi	gaai	gaa
Historical Thai phonetic values	zumh	caï	rɯaih	graih	gaʔ
English glosses	to hide	heart	forever, constantly	to yearn	ptl.
Zhengzhang's English translation	Hidden forever in my heart, ah! is my adoration and longing.

Zhengzhang notes that ‘evening, night, dark’ bears the C tone in Wuming Zhuang xam^C2 and ɣam^C2 ‘night’. The item raa normally means ‘we inclusive’ but in some places, e.g. Tai Lue and White Tai ‘I’.