According to Michel Ferlus, the ethnonyms Tai/Thai (or Tay/Thay) would have evolved from the etymon *k(?)ri: 'human being' through the following chain: k?ri: > k?li: > k?di:/k?daj (-l- > -d- shift in tense sesquisyllables and probable diphthongization of -i: > -aj). This in turn changed to di:/daj (presyllabic truncation and probable diphthongization -i: > -aj). And then to *dajA (Proto-Southwestern Tai) > t?ajA2 (in Siamese and Lao) or > tajA2 (in the other Southwestern and Central Tai languages by Li Fangkuei). Michel Ferlus' work is based on some simple rules of phonetic change observable in the Sinosphere and studied for the most part by William H. Baxter (1992).
The ethnonym and autonym of the Lao people (l?o ?) together with the ethnonym Gelao (G?l?o ), a Kra population scattered from Guìzh?u (China) to North Vietnam, and Sino-Vietnamese 'Jiao' as in Jiaozhi (ji?o zh? ), the name of North Vietnam given by the ancient Chinese, would have emerged from the Austro-Asiatic*k(?)ra:w 'human being'.
The etymon *k(?)ra:w would have also yielded the ethnonym Keo/ Kæw k?:wA1, a name given to the Vietnamese by Tai speaking peoples, currently slightly derogatory. In fact, Keo/ Kæw k?:wA1 was an exonym used to refer to Tai speaking peoples, as in the epic poem of Thao Cheuang, and was only later applied to the Vietnamese. In Pupeo (Kra branch), kew is used to name the Tay (Central Tai) of North Vietnam.
The name "Lao" is used almost exclusively by the majority population of Laos, the Lao people, and two of the three other members of the Lao-Phutai subfamily of Southwestern Tai: Isan speakers (occasionally), the Nyaw or Yaw and the Phu Thai.
The Zhuang in China do not constitute an autonymic unity: in various areas in Guangxi they refer to themselves as powC2?u:?B2, p?oB2t?ajA2, powC2ma:nA2, powC2ba:nC1, or powC2lawA2, while those in Yunnan use the following autonyms: puC2no?A2, buB2dajA2, or buC2jajC1 (=Bouyei, bùyi ). The Zhuang do not constitute a linguistic unity either, because Chinese authorities include within this group some distinct ethnic groups such as the Lachi speaking a Kra language.
The Nung living on both sides of the Sino-Vietnamese border have their ethnonym derived from clan name Nong (? / ?), whose bearers dominated what are now north Vietnam and Guangxi in the 11th century AD. In 1048, a Nong general, Nong Zhigao, revolted against Annamese rule, and then marched eastwards to besiege Guangzhou in 1052.
Another name that's shared between the Nung, the Tay, and the Zhuang living along the Sino-Vietnamese border is Tho, which literally means autochthonous.
Map showing linguistic family tree overlaid on a geographic distribution map of Tai-Kadai family. This map only shows general pattern of the migration of Tai-speaking tribes, not specific routes, which would have snaked along the rivers and over the lower passes.
The Tai peoples, from Guangxi began to move southwestward in the first millennium CE, eventually spreading across the whole of mainland Southeast Asia. Based on layers of Chinese loanwords in proto-Southwestern Tai and other historical evidence, Pittayawat Pittayaporn (2014) proposes that the southwestward migration of Tai-speaking tribes from the modern Guangxi and northern Vietnam to the mainland of Southeast Asia must have taken place sometime between the 8th-10th centuries. Tai speaking tribes migrated southwestward along the rivers and over the lower passes into Southeast Asia, perhaps prompted by the Chinese expansion and suppression. Chinese historical texts record that, in 722, 400,000 'Lao'[a] rose in revolt behind Mai Thúc Loan, who declared himself the king of Nanyue in Guangdong. After the 722 revolt, some 60,000 were beheaded. In 726, after the suppression of a rebellion by a 'Lao' leader in the present-day Guangxi, over 30,000 rebels were captured and beheaded. In 756, another revolt attracted 200,000 followers and lasted four years. In the 860s, many local people in what is now north Vietnam sided with attackers from Nanchao, and in the aftermath some 30,000 of them were beheaded. In the 1040s, a powerful matriarch-shamaness by the name of A Nong, her chiefly husband, and their son, Nong Zhigao, raised a revolt, took Nanning, besieged Guangzhou for fifty seven days, and slew the commanders of five Chinese armies sent against them before they were defeated, and many of their leaders were killed. As a result of these three bloody centuries, the Tai began to migrate southwestward.
The Tai, from their new home in Southeast Asia, were influenced by the Khmer and the Mon and most importantly Buddhist India.
Kra-Dai (Tai-Kadai) migration route according to James R. Chamberlain (2016).
Map of the Chinese plain at the start of the Warring States Period in the 5th century BC, showing the locations of the states of Chu, Wu, and Yue.
The high diversity of Kra-Dai languages in southern China points to the origin of the Kra-Dai language family in southern China. The Tai branch moved south into Southeast Asia only around 1000 AD.
James R. Chamberlain (2016) proposes that Tai-Kadai (Kra-Dai) language family was formed as early as the 12th century BCE in the middle Yangtze basin, coinciding roughly with the establishment of the Chu fiefdom and the end of the Shang dynasty. Following the southward migrations of Kra and Hlai (Rei/Li) peoples from the ancient state of Chu around the 8th century BCE, the Be-Tai people started to break away to the east coast in the present-day Zhejiang, in the 6th century BCE, establishing the state of Yue. After the destruction of the state of Yue by Chu army around 333 BCE, Yue people (Be-Tai) began to migrate southwards along the east coast of China to what are now Guangxi, Guizhou and northern Vietnam, forming Luo Yue (Central-Southwestern Tai) and Xi Ou (Northern Tai).
Chamberlain's proposal of the Chu ? Urheimat of Tai-Kadai is supported by unearthed epigraphic materials, which show clear substrate influence, predominantly from Tai-Kadai. One of the most notable items is the Chu graph for "one, once" written as (? < OC*nn) in the E jun qijie ? bronze tally and in Warring States bamboo inscriptions, which represents a Tai-Kadai areal word. The following are some Tai-Kadai words in Chu ? bronze inscriptions and early Chinese literature identified by Wolfgang Behr:
In a paper published in 2004, Linguist Laurent Sagart hypothesized that the proto-Tai-Kadai language originated as an Austronesian language that migrants carried from Taiwan to mainland China. Afterwards, the language was then heavily influenced by local languages from Sino-Tibetan, Hmong-Mien, or other families, borrowing much vocabulary and convergingtypologically. Later, Sagart (2008) introduces a numeral-based model of Austronesian phylogeny, in which Tai-Kadai is considered as a later form of FATK,[b] a branch of Austronesian belonging to subgroup Puluqic developed in Taiwan, whose speakers migrated back to the mainland, both to Guangdong, Hainan and north Vietnam around the second half of the 3rd millennium BCE. Upon their arrival in this region, they underwent linguistic contact with an unknown population, resulting in a partial relexification of FATK vocabulary. On the other hand, Weera Ostapirat supports a coordinate relationship between Tai-Kadai and Austronesian, based on a number of phonological correspondences. The following are Tai-Kadai and Austronesian lexical items showing the genetic connection between these two language families:
The connection between Austronesian and Tai-Kadai can also be found in some common cultural practices. Roger Blench (2008) demonstrates that dental evulsion, face-tatooing, teeth-blackening and snake cults are shared between the Taiwanese Austronesian and Tai-Kadai population in Southern China.
A recent genetic and linguistic analysis in 2015 showed great genetic homogenity between Kra-Dai speaking people, suggesting a common ancestry and a large replacement of former non-Kra-Dai groups in Southeast Asia. Kra-Dai populations are closest to southern Chinese and Taiwanese populations..
Tai social organization
The Tai practice a type of feudal governance that is fundamentally different from that of the Chinese, and is especially adapted to state formation in ethnically and linguistically diverse montane environments centered on valleys suitable for wet-rice cultivation. The form of society is a highly stratified one.
Listed below are lesser-known Tai peoples and languages.
Bajia - 1,106 people in Mengkang Village , Meng'a Township , Menghai County, Yunnan, who speak a language closely related to Tai Lü. They are classified by the Chinese government as ethnic Dai people. In Meng'a Town, they are in the village clusters of Mengkang  (in Shangnadong , Xianadong , and Mandao ), Hejian  (in villages 6, 7, and 8), and Najing  (in villages 6, 7, and 8). Zhang (2013) reports that there are 218 households and 816 people in 14 villages, and that the Bajia language is mutually intelligible with Tai. Another group of Bajia people in Manbi Village , Menghun Town , Menghai County, Yunnan (comprising 48 households and 217 persons) has recently been classified by the Chinese government as ethnic Bulang people.
Tai Beng  - over 10,000 people in Yunnan Province, China. Also in Shan State, Myanmar. In China, they are in Meng'aba , Mengma Town , Menglian County (in the three villages of Longhai , Yangpai , and Guangsan ); Mangjiao Village , Shangyun Township , Lancang County (in the 2 villages of Mangjing  and Mangna ); Cangyuan County (in Mengjiao and Mengdong townships); Gengma County (in Mengding and Mengsheng townships); Ruili City (in small populations scattered along the border).
Han Tai - 55,000 people in the Mengyuan County, Xishuangbanna Prefecture, Yunnan, China. Many Han Tai also speak Tai Lu (Shui Tai), the local lingua franca.
Huayao Tai - 55,000 people (as of 1990) in Xinping and Mengyang Counties, Yunnan. It may be similar to Tai Lu.
Lao Ga - 1,800 people mostly in Ban Tabluang, Ban Rai District, Uthai Thani Province, Thailand. Their language is reportedly similar to Lao Krang and Isan.
Lao Krang - 50,000+ people in the provinces of Phichit, Suphan Buri, Uthai Thani, Chai Nat, Phitsanulok, Kamphaeng Phet, Nakhon Pathom and Nakhon Sawan, Thailand. Their language is similar to Isan and Lao. Tai Krang is not to be confused with Tai Khang, a Tai-speaking group of Laos numbering 5,000 people.
Lao Lom - 25,000 people in Dan Sai District of Loei Province (locally known as the Lao Loei or Lao Lei), Lom Kao District of Phetchabun Province, and Tha Bo District of Nong Khai Province (locally known as the Tai Dan). The Lao Lom were first studied by Joachim Schliesinger in 2001. Unclassified Southwestern Tai language.
Lao Ngaew - 20,000 to 30,000 people in Lop Buri Province (especially Ban Mi and Khok Samrong districts), the Tha Tako District of Nakhon Sawan Province and scattered parts of Singburi, Saraburi, Chaiyaphum, Phetchabun, Nong Khai and Loei provinces. Originally from eastern Xiengkhouang and western Huaphan provinces of Laos. Their language is similar to Isan.
Lao Ti - 200 people in the 2 villages of Ban Goh and Nong Ban Gaim in Chom Bung District, Ratchaburi Province, Thailand. Originally from Vientiane in Laos. Their language is similar to Lao and Isan.
Lao Wiang - 50,000+ people in Prachinburi, Udon Thani, Nakhon Sawan, Nakhon Pathom, Chai Nat, Lopburi, Saraburi, Phetchaburi and Roi Et. Originally from Wiang Chan (Vientiane) in Laos. Their language is similar to Lao.
Paxi - 1,000+ people (as of 1990) in 2 villages 8 km from Menghai Town, at the foot of Jingwang Mountain in Xishuangbanna.
Tai Bueng - 5,700 people in 2 villages of Phatthana Nikhom District, Lopburi Province, Thailand. The Tai Bueng live in the villages of Ban Klok Salung (pop. 5,000) and Ban Manao Hwan (pop. 600). Unclassified Tai language.
Tai Doi ('mountain people') - 230 people (54 families) as of 1995 in Long District of Luang Namtha, Laos. Their language is likely Palaungic.
Tai Gapong ('brainy Tai') - 3,200+ people; at least 2,000 people (500+ households) in Ban Varit, Waritchapum District, Sakhon Nakhon Province; also live with the Phutai and Yoy. The Tai Gapong claim to have originated in Borikhamxai Province, Laos.
Tai He - 10,000 people in Borikhamxai Province, Laos: in Viangthong and Khamkeut Districts; also in Pakkading and Pakxan Districts. Unclassified Tai language.
Tai Kaleun - 7,000 people mostly in Khamkeut District, Borikhamxai Province, Laos; also in Nakai District. 8,500 people in Thailand: the provinces of Mukdahan (Don Tan and Chanuman districts), Nakhon Phanom (Muang District) and parts of Sakhon Nakhon Province. The Tai Kaleung speak a Lao dialect.
Tai Khang - 5,600+ people in Xam-Tai District, Houaphan Province, Laos; also in Nongkhet District of Xiangkhoang Province, and Viangthong District of Borikhamxai Province. Unclassified Tai language.
Tai Kuan (Khouane) - 2,500 people in Viengthong District, Borikhamxai Province, Laos: near the banks of the Mouan River.
Tai Laan - 450 people in a few villages of Kham District, Xiangkhoang Province, Laos. Unclassified Tai language.
Tai Loi - 1,400 people in Namkham, Shan State, Burma; 500 people in Long District, Luang Namtha Province, Laos; possibly also in Xishuangbanna Prefecture, China, since some Tai Loi in Burma say they have relatives in China. Their language may be related to and probably also closely related to Palaung Pale.
Tai Men - 8,000 people in Borikhamxai Province, Laos: mostly in Khamkeut District, but also in Vienthong, Pakkading, and Pakxan Districts. They speak a Northern Tai language.
Tai Meuiy - 40,000+ people in Borikhamxai, Khammouan, Xiengkhouang, and Houaphan (just outside the town of Xam Neua) provinces of Laos. Their language is reportedly similar to Tai Dam and Tai Men.
Tai Nyo - 13,000 people in Pakkading District, Borikhamxai Province, Laos; 50,000 people in northeastern Thailand, where they are better known as Nyaw. Similar to Lao of Luang Prabang.
Tai Pao - 4,000 people in Viangthong, Khamkeut and Pakkading districts of Borikhamxai Province, Laos. They live near the Tai He and may be related to them. Unclassified Tai language.
Tai Peung - 1,000 people in Kham District, Xiengkhouang Province, Laos. They live near the Tai Laan and Tai Sam. Unclassified Tai language.
Tai Pong - perhaps as many as 100,000 people in along the Honghe River of southeastern, Yunnan, China, and possibly also in northern Vietnam. Subgroups include the Tai La, Tai You, and probably also Tai Ya (which includes Tai Ka and Tai Sai). Unclassified Tai language.
Tai Sam - 700 people in Kham District, Xiengkhuoang Province, Laos. Neighboring peoples include the Tai Peung and Tai Laan. Unclassified Tai language.
Tai Song - 45,000+ people in Phetchabun, Phitsanulok, Nakhon Sawan (Tha Tako District), Ratchaburi (Chom Bung District), Suphan Buri (Song Phinong District), Kanchanaburi, Chumphon and Nakhon, and Pathom (Muang District). Also called Lao Song. They are a subgroup of the Tai Dam.
Tai Wang - 10,000 people in several villages in Viraburi District, Savannakhet Province, Laos; 8,000 in and around the city of Phanna Nikhom, Sakhon Nakhon Province, Thailand. Their language is related to but distinct from Phutai.
Tai Yuan ('Northern Thai') - 6,000,000 people in Northern Thailand and possibly 10,000 people in Houayxay and Pha-Oudom districts of Bokeo Province, Luang Namtha District of Luang Namhta Province, Xai District of Oudomxai Province, and Xaignabouri District of Xaignabouri Province. They speak a Southwestern Tai language.
Tak Bai Thai - 24,000 people in southern Thailand (in Narathiwat, Pattani, and Yala provinces) and northern Malaysia. Their name comes from the town of Tak Bai in Narathiwat Province. Their language is highly different from nearby Southern Thai dialects, and may be related to the Sukkothai dialect further up north.
Kap Kè ('gekko' people) now refer to themselves as Nyo. The Nyo proper reside mostly along the Mekong between Hinboun and Pakxanh and also in Thailand. The Kap Kè claim they are the same as the Nyo of Ban Khammouane in Khamkeut District, Bolikhamsai province, Laos. Another Kap Kè group of about 40 households originally from Sop Khom has now resettled in Sop Phouan. This group claims to be from Ban Faan, about 1 kilometer from Sop Khom.
Phuk (sometimes pronounced without the final -k as Phu') - According to themselves as well as other ethnic groups, the Phuk closely resemble the Kap Kè and originally came from nearby locations, referred to as phiang phuk and phiang Kap Kè. They were originally from the villages of Fane, Ka'an and Vong Khong.
Thay Bo - located on the Nakai plateau in central Laos, along the middle Hinboun River, east of the Kong Lo cave and the Phon Tiou tin mine, and in Ban Na Hat and near Na Pè, close to the Vietnamese border. Bo means 'a mine,' referring people who worked either in the salt mines on the Nakai Plateau, or at the tin mine. Many older generation people speak a Vietic language as well, apparently Maleng, as spoken in the village of Song Khone on the Nam Sot River, a main tributary of the Nam Theun, although this has not been verified.
Kha Bo - In 1996, the Bo of Sop Ma village reported that they were "born from the Kha," a reference to their Vietic origins, and in that village there was intermarriage with the Maleng of Song Khone. They are distinct from the Thay Bo of Hinboun. The Kha Bo on the Nakai plateau speak Nyo, whereas nowadays the Thay Bo of Hinboun speak Lao or Kaleung. The Ahoe, original inhabitants of the northwestern part of the Nakai Plateau, had also been relocated to Hinboun during the Second War of Indochina, and returned to their homeland speaking Hinboun Nyo as a second language.
In Burma, there are also various Tai peoples that are often categorized as part of a larger Shan ethnicity (see Shan people#Tai groups).
The most significant communities of Tai peoples in Europe are in the Lao communities of the United Kingdom, France, Germany and Switzerland, the Isan communities of the United Kingdom and Iceland, the Thai communities of Finland, Iceland and Norway, the Tai Dam and Tay communities of France, and the Southern Thai community of the United Kingdom.
^The term "Lao" used in this context refers to Tai-Kadai speaking peoples resided in what are now Guangdong, Guangxi, and northern Vietnam in general. It is unnecessarily applied solely to the ancestor of the Lao.
^Cai X, Qin Z, Wen B, Xu S, Wang Y, et al. (2011), "Human Migration through Bottlenecks from Southeast Asia into East Asia during Last Glacial Maximum Revealed by Y Chromosomes." PLoS ONE 6(8): e24282. doi:10.1371/journal.pone.0024282
^ abZhang X, Kampuansai J, Qi X, Yan S, Yang Z, et al. (2014), "An Updated Phylogeny of the Human Y-Chromosome Lineage O2a-M95 with Novel SNPs." PLoS ONE 9(6): e101020. doi:10.1371/journal.pone.0101020
^He J-D, Peng M-S, Quang HH, Dang KP, Trieu AV, et al. (2012), "Patrilineal Perspective on the Austronesian Diffusion in Mainland Southeast Asia." PLoS ONE 7(5): e36437. doi:10.1371/journal.pone.0036437
^Xiaoming Zhang, Shiyu Liao, Xuebin Qi, et al. (2015), "Y-chromosome diversity suggests southern origin and Paleolithic backwave migration of Austro-Asiatic speakers from eastern Asia to the Indian subcontinent." Scientific Reports 5, 15486; doi: 10.1038/srep15486.
^Srithawong, Suparat; Srikummool, Metawee; Pittayaporn, Pittayawat; Ghirotto, Silvia; Chantawannakul, Panuwan; Sun, Jie; Eisenberg, Arthur; Chakraborty, Ranajit; Kutanan, Wibhu (2015). "Genetic and linguistic correlation of the Kra-Dai-speaking groups in Thailand". Journal of Human Genetics. 60 (7): 371-380. doi:10.1038/jhg.2015.32. ISSN1435-232X. PMID25833471.
^Chazee, Laurent. 1998. Rural and ethnic diversities in Laos with special focus on the northern provinces. Presented for the Workshop on "Rural and Ethnic diversities in Laos with special focus on Oudomxay and Sayabury development realities", in Oudomxay province, 4-5 June 1998. SESMAC projects Lao/97/002 & Lao/97/003: Strengthening Economic and Social Management Capacity, Sayabury and Oudomxay provinces.
Sagart, Laurent (2008). "The expansion of Setaria farmers in East Asia". In Sanchez-Mazas, Alicia; Blench, Roger; Ross, Malcolm D.; Peiros, Ilia; Lin, Marie (eds.). Past Human Migrations in East Asia: Matching Archaeology, Linguistics and Genetics (Routledge Studies in the Early History of Asia) 1st Edition. Routledge. pp. 133-157. ISBN978-0-415-39923-4.