Tai migration (8th–12th century) '' of southeastern China The ancestors of the Lao people were speakers of Southwestern Tai dialects that migrated from what is now southeastern China, specifically what is now
Guangxi and northern
Vietnam where the diversity of various Tai languages suggests an
Urheimat. The Southwestern Tai languages began to diverge from the Northern and Central branches of the Tai languages, covered mainly by various
Zhuang languages, sometime around 112 CE, but likely completed by the
sixth century. Due to the influx of
Han Chinese soldiers and settlers, the end of the
Chinese occupation of Vietnam, the fall of
Jiaozhi and turbulence associated with the decline and fall of the
Tang dynasty led some of the Tai peoples speaking Southwestern Tai to flee into Southeast Asia, with the small-scale migration mainly taking place between the
eighth and
twelfth centuries. The Tais split and followed the major river courses, with the ancestral Lao originating in the Tai migrants that followed the
Mekong River.
Divergence and convergence As the Southwestern Tai-speaking peoples diverged, following paths down waterways, their dialects began to diverge into the various languages today, such as the Lao-Phuthai languages that developed along the Mekong River and includes Lao and its Isan sub-variety and the Chiang Saen languages which includes the Central Thai dialect that is the basis of Standard Thai. Despite their close relationship, there were several phonological divergences that drifted the languages apart with time such as the following examples: ; PSWT *
ml > Lao /m/, > Thai /l/ {{fs interlinear|indent=3 ; PSWT *
r (initial) > Lao /h/, > Thai /r/ {{fs interlinear|indent=3 ; PSWT *
ɲ > Lao /ɲ/, > Thai /j/ {{fs interlinear|indent=3 Similar influences and proximity allowed for both languages to converge in many aspects as well. Thai and Lao, although separated, passively influenced each other through centuries of proximity. For instance, the Proto-Southwestern Tai *
mlɛːŋ has produced the expected Lao /m/ outcome
maeng (
mèng, ) and the expected Thai /l/ outcome
laeng ( ), although this is used only in Royal Thai or restricted academic usage, with the common form
malaeng ( ), actually an archaic variant. In slang and relaxed speech, Thai also has
maeng ( ), likely due to influence of Lao. The heavy imprint of Khmer is shown in the genetics of Tai speakers, with samples from Thai and Isan people of Lao descent showing proof of both the Tai migration but also intermarriage and assimilation of local populations. Scholars such as Khanittanan propose that the deep genetic and linguistic impact of the autochthonous Khmer and their language indicates that the earliest days of
Ayutthaya had a largely bilingual population. Although evidence and research in Lao is lacking, major Lao cities were known to have been built atop existing Khmer settlements, suggesting assimilation of the locals. Isan and Lao commonly use a Khmer loan not found in Thai,
khanong (
khanông, ), 'doorframe', from Khmer
khnâng (, ), which means 'building', 'foundation' or 'dorsal ridge'. Indic languages also pushed Thai and Lao closer together, particularly Sanskrit and Pali loan words that they share. Many Sanskrit words were adopted via the Khmer language, particularly concerning Indian concepts of astrology, astronomy, ritual, science, kingship, art, music, dance and mythology. New words were historically coined from Sanskrit roots just as European languages, including English, share Greek and Latin roots used for these purposes, such as 'telephone' from Greek roots
tēle, 'distant' and
phōnē which was introduced in Thai as
thorasap (, ) and spread to Isan as
thorasap (
thôrasap, ) from Sanskrit
dura (, ), 'distant', and
śabda (, ), 'sound'. Indic influences also came via
Pali, the
liturgical language of
Theravada Buddhism. The effects of Khmer and Indic vocabulary did not affect all the Tai languages of Southeast Asia equally. The
Tai Dam of northern Vietnam were shielded from the influence of the Khmer language and the Indic cultural influences that came with them and remain traditionally a non-Buddhist people. Although the Tai Dam language is a Chiang Saen language, albeit with a lexicon and
phonology closer to Lao, the lack of Khmer, Sanskrit and Pali loan words makes the language unintelligible to Thai and Lao speakers.
Lan Xang (1354–1707) in Nakhon Phanom. Built in the 16th century over earlier Khmer ruins when Isan was part of Lan Xang, the temple is an important place of pilgrimage, attracting Lao from Laos as well as Isan to its temple festivals. Taking advantage of rapid decline in the Khmer Empire, Phra Chao
Fa Ngoum ( ) defeated the Khmer and united the Tai
mueang of what is now Laos and Isan into the
mandala kingdom of
Lan Xang in 1354. Fa Ngoum was a grandson of the ruler of
Muang Xoua (RTGS
Mueang Sawa), modern-day Louang Phrabang. Lan Xang was powerful enough to thwart Siamese designs from their base at
Sukhothai and later
Ayutthaya. Khmer, and Sanskrit via Khmer, continued to influence the Lao language. Since Fa Ngoum was raised in the Khmer court, married to a Khmer princess and had numerous Khmer officials in his court, a now-extinct speech register known as
rasa sap ( ) was developed to address or discuss the king and high-ranking clergy. Khmer and Sanskrit also contributed many belles-lettres as well as numerous technical, academic and cultural vocabulary, thus differentiating the Lao language from the tribal Tai peoples, but pushing the language closer to Thai, which underwent a similar process. The end of the Lao monarchy in 1975 made the Lao
raxasap obsolete, but as Thailand retains its monarchy, Thai
rachasap is still active. Lao literature was also given a major boost with the brief union of Lan Xang with Lan Na during the reign of
Xay Xétthathirat ( ) (1546–1551). The libraries of
Chiang Mai were copied, introducing the
tua tham (BGN/PCGN
toua tham, RTGS
tua tham) or 'dharma letters' which was essentially the
Mon-influenced script of Lan Na but was used in Lao specifically for religious literature. With Theravada Buddhism came its liturgical language, Pali, an Indic language derived from the
Prakrit. Many Pali terms existed alongside earlier Sanskrit borrowings or were Sanskritized, leading to doublets such as Sanskrit
maitri ( ) and Pali
metta ( ), both of which signify 'loving kindness' although the Sanskrit term is more generally used for 'friendship'. The spread of Theravada Buddhism spread literacy, as monks served as teachers, teaching reading and writing as well other basic skills to village boys, and the
Tai Noi script was used for personal letters, record-keeping, and signage, as well as to record short stories and the
klon ( ) poetry that were often incorporated into traditional folksongs. Although the kingdoms remained nominally autonomous, the Siamese demanded tribute and taxes, kept members of the respective royal houses as hostages to ensure loyalty and required the three Lao kings to come to the capital several times a year to hold an audience with the Siamese king. When the kingdoms revolted, the Siamese armies retaliated by rounding up entire villages, tattooing them to mark them as slaves and forced to settle what is now Isan, forced to serve as soldiers or manpower in
corvée projects to build roads, to grow food, build canals, or serve as domestics. The greatest population transfer occurred after the
Laotian Rebellion by Chao
Anouvông (, ) in 1828 which led to the death of Anouvông and most of his family. The Siamese abducted nearly the entire population of Vientiane and its surrounding area and forced them to the right bank. Continued raids of people continued until the end of the nineteenth century. In addition to forced transfers, many Lao were encouraged to settle in Isan, with some disillusioned princes granted lofty titles in exchange for loyalty and taxation, robbing the Lao kings of taxation and wealth as well as what little nominal authority they had left. This greatly expanded the Lao population of Isan and caused assimilation of the local peoples into the mix, a process that is occurring on a smaller scale even now. Siamese intervention paradoxically strengthened the Lao character of the region as the Siamese left the Lao areas alone as long as they continued to produce rice and continued to pay tribute. Direct Siamese rule did not extend past
Nakhon Ratchasima, and the Lao
mueang, whether paying their tribute directly to Bangkok or the remaining Lao kings and princes, were still nominally part of the separate kingdoms. Temples built in what is now Isan still featured the Tai Noi script on its murals and although Siam would intervene in some matters, daily administration was still left to the remaining kings and various Lao princes that served as governors of the larger
mueang. The result of the population movements re-centered the Lao world to the right bank, as today, if Isan and Lao speakers are counted together, Isan speakers form 80 percent of the Lao-speaking population.
French Laos (1893–1953) During French rule, missing words for new technologies and political realities were borrowed from French or Vietnamese, repurposed from old Lao vocabulary as well as coined from Sanskrit. These Sanskrit-derived neologisms were generally the same, although not always, as those that developed in Thai. Whilst previously written in a mixture of etymological and phonetical spellings, depending on audience or author, Lao underwent several reforms that moved the language towards a purely phonetical spelling. During the restoration of the king of Louang Phabang as King of Laos under the last years of French rule in Laos, the government standardized the spelling of the Lao language, with movement towards a phonetical spelling with preservation of a semi-etymological spelling for Pali, Sanskrit and French loan words and the addition of archaic letters for words of Pali and Sanskrit origin concerning Indic culture and Buddhism.
Independence and Communist rule (1953–present) Spelling reforms under the communist rule of Laos in 1975 were more radical, with the complete abolition of semi-etymological spelling in favor of phonetical spelling, with the removal of silent letters, removal of special letters for Indic loan words, all vowels being written out explicitly and even the elimination or replacement of the letter 'ຣ' (but usually pronounced /l/) in official publications, although older people and many in the Lao diaspora continue to use some of the older spelling conventions. ==Dialects==