Thai script in the context of "Writing direction"

Mass migration of Tai peoples from China (Guangxi) to Mainland Southeast Asia and Northern Thailand occurred between the 8th-10th century. The Mainland region was ruled by the Khmer Empire since 800 CE. The Thai established their own kingdoms: the semi-legendary Singhanavati Kingdom (691 BCE–638 CE) evolved into the Ngoenyang Kingdom (638–1292). In 1220, the Khmer controlled Sukhothai was conquered by the Thais and made the capital of the Sukhothai Kingdom. By 1220, the long declining Khmer Empire was mostly overrun by Thais. By the 13th century, the Sukhothai Kingdom (1238–1438) had replaced the Mon kingdoms in Central Thailand. During the reign of King Ramkhamhaeng the Thai script was created in 1283, the arts flourished, Thai institutions were developed, and people called themselves "Thai" as freed people from foreign rule.

In 1351, the Suphannabhum city-state (modern-day Suphan Buri), and Lavo city-state (modern-day Lop Buri) merged into the Ayutthaya Kingdom which was founded near the Chao Phraya River. Duarte Fernandes was the first European to arrive in Ayutthaya in 1511. Siam became the popular international name for Thailand.

Northern Thailand the oldest region in Thailand the main ethnic group Tai-Lue established their own kingdoms: the semi-legendary Singhanavati Kingdom (691 BCE–638 CE) evolved into the Ngoenyang Kingdom (638–1292). In 1220, the Khmer controlled Sukhothai was conquered by the Thais and made the capital of the Sukhothai Kingdom. By 1220, the long declining Khmer Empire was mostly overrun by Thais. By the 13th century, the Sukhothai Kingdom (1238–1438) had replaced the Mon kingdoms in Central Thailand. During the reign of King Ramkhamhaeng the Thai script was created in 1283, the arts flourished, Thai institutions were developed, and people called themselves "Thai" as freed people from foreign rule.

In 1351, the Suphannabhum city-state (modern-day Suphan Buri), and Lavo city-state (modern-day Lop Buri) merged into the Ayutthaya Kingdom (Tai-Lue from the Northern+Monic from Chao Phra Ya river basin = Siamese Kingdom) which was founded near the Chao Phraya River. Duarte Fernandes was the first European to arrive in Ayutthaya in 1511.

Old Khmer is the oldest attested stage of the Khmer language, an Austroasiatic language historically and presently spoken across Cambodia, Southern Vietnam, and parts of Thailand and Laos. It is recorded in inscriptions dating from the early 7th century until the first few decades of the 15th century. Such inscriptions, spanning nearly a millennium and numbering well over a thousand, present one of the most extensive sources of documentation in Southeast Asia.

Old Khmer was written in an early variant of the Khmer script derived from Pallava, a southern variant of Brahmi, and in turn became the basis of the scripts used for Thai and Lao. Along with Brahmi and Indian influence on Cambodia, Old Khmer saw an influx of Sanskrit loanwords in the domains of religion, philosophy, and to a lesser extent, politics. Despite this, Old Khmer retained a prototypical Austroasiatic typology in phonology, syntax, and morphology, being sesquisyllabic, analytic, having a rich system of derivational affixes.

The Grantha script (Sanskrit: 𑌗𑍍𑌰𑌨𑍍𑌥𑌲𑌿𑌪𑌿, romanized: granthalipi; Tamil: கிரந்த எழுத்து, romanized: Granta eḻuttu; Malayalam: ഗ്രന്ഥലിപി, romanized: granthalipi) is a classical South Indian Brahmic script, found particularly in Tamil Nadu and Kerala. Originating from the Pallava script, the Grantha script is related to Tamil and Vatteluttu scripts. The modern Malayalam script of Kerala is a direct descendant of the Grantha script. The Southeast Asian and Indonesian scripts such as Thai and Javanese respectively, as well as South Asian and Sri Lankan scripts such as Tigalari and Sinhalese scripts respectively, are derived or closely related to Grantha through the early Pallava script. The Pallava script or Pallava Grantha emerged in the 4th century CE and was used until the 7th century CE, in India. This early Grantha script was used to write Sanskrit texts, inscriptions on copper plates and stones of Hindu temples and monasteries. It was also used for classical Manipravalam – a language that is a blend of Sanskrit and Tamil. From it evolved Middle Grantha by the 7th century, and Transitional Grantha by about the 8th century, which remained in use until about the 14th century. Modern Grantha has been in use since the 14th century and into the modern era, to write classical texts in Sanskrit and Dravidian languages. It is also used to chant hymns and in traditional Vedic schools.

The Tamil purist movement of the colonial era sought to purge the Grantha script from use and use the Tamil script exclusively. According to Kailasapathy, this was a part of Tamil nationalism and amounted to regional ethnic chauvinism.

Nyiakeng Puachue Hmong (Hmong: 𞄐𞄦𞄲𞄤𞄎𞄫𞄰𞄚𞄧𞄲𞄤𞄔𞄬𞄱‎; RPA: Ntawv Nyiajkeeb Puajtxwm Hmoob) is an alphabet script devised for White Hmong and Green Hmong in the 1980s by Reverend Chervang Kong for use within his United Christians Liberty Evangelical Church. The church, which moved around California, Minnesota, Wisconsin, North Carolina, Colorado, and many other states, has used the script in printed material and videos. It is reported to have some use in Laos, Thailand, Vietnam, France, and Australia.

The script bears strong resemblance to Thai script in structure and form and characters inspired from the Hebrew alphabet, although the characters themselves are different. It contains 36 consonant characters, 9 vowel characters, and 7 combining tone characters. There are also 5 characters for determinatives used to indicate that the preceding noun is the name of a person, place, thing, vertebrate or invertebrate animal, or a pet name for the animal. Determinatives are not pronounced, but help distinguish homophones. They appear as the last character in a word, and are not separated by a space.