Early human presence has been identified from sites such as Lang Rongrien and the Spirit Cave, evidence such as stone tools and fossils suggest that hunter-gather communities lived in the region from at least 40 000 BCE.
Early inhabitants moved seasonally through forests, valleys and coastal areas with the seasons, hunting deer, wild pigs, monkeys and other animals, fishing and gathering fruit and nuts.

Farming gradually replaced hunter-gatherer lifestyles and rice cultivation became important along river valleys and in the fertile lowlands. Animals such as pigs, dogs and cattle were domesticated and permanent settlements were established. As food supplies increased so did the population with villages made up of wooden, bamboo and thatch houses, situated along rivers and fertile plains.
Pottery was widespread and stone tools improved, weaving and textile production was commonplace. Human bodies have been found alongside goods in graves, indicating early ritual and belief in the afterlife.

As the bronze age dawned tools were revolutionised; metalworkers held important roles within the community.
Ban Chiang is an important archaeological site found in the north of Thailand, the pottery found here was painted red with distinct swirling patterns.
The long distance trade of copper, tin, textiles, salt and shells looks to have been prevalent in South East Asia at this time among some societies. Whilst others remained in close knit communities.

The use of iron in tools evolved farming in the area. Small farming villages gradually evolved towards more powerful chiefdoms. With power centred around those that controlled farmland, water supplies and trade routes. Important settlements included Ban Non War and Noen U-Loke along the Mun River valley. Trade Networks connected the land to the regions that are modern day Vietnam, Cambodia, Myanmar and China.
The Kingdom of Funan (1 CE – 550 CE) in modern day Cambodia began to influence the area, as did Indian merchants, introducing Hinduism, Buddhism and Sanskrit writings. Local rulers picked up Indian titles and the Hindu concepts of Kingship
Langkasuka evolved in Southern Thailand around 100 CE under strong Hindu influence with Buddhism ideologies also present. It was mentioned in Chinese records and had maintained diplomatic contact with China. Langkasuka controlled trade between the Indian Ocean and South China Sea.

Dvaravati city states dominated central Thailand from around 600 – Mon speaking Buddhist kingdoms centred on cities such as Nakhon Pathom, U Thong and Lopburi.
The rulers of the Dvaravati kingdoms adopted Indian cultural concepts and Theravada Buddhism led as the dominant religion. Buddhist monasteries, stupas and Dharma wheels were constructed of stone throughout the region.
The city state of Hariphunchai was founded around 661 in northern Thailand, its capital residing in Lamphun. Traditionally it was established by Queen Chamadevi, a Mon ruler from Dvaravati. Hariphunchai became an important centre for Buddhism.

During this period, southern Thailand became increasingly influenced by a powerful maritime Sumatran empire – Srivijaya. Srivijaya controlled the trade route through the Strait of Malacca. Also a Buddhist kingdom the ports around southern Thailand became rich from trade.

In the 9th century and onwards, the Khmer Empire (based in Angkor) extended its influence into eastern and central Thailand. Temples, reservoirs and roads were constructed by the Khmers. By the 11th and 12th centuries, most of central Thailand fell under Khmer influence. However Hariphuncai remained independent in the north and the southern regions maintained links with Srivijaya.

Two local Thai leaders, Pho Khun Bang Klang Hao and Pho Khun Pha Mueang revolted against Khmer authority in 1238 and established the Kingdom of Sukhothai. With Bang Klang Hao ruling as King Si Inthrathit.
Sukhothai was the first major Thai kingdom and Tai-speaking peoples rose as the dominant political regional force.
Sukhothai reached its height Under King Ramkhamhaeng the Great (1279 – 1298), spanning much of present day Thailand and influencing neighbouring regions.
After Ramkhamhaeng’s death, Sukhothai fragmented as subject states grew in independence.

King Ramathibodi I established the Kingdom of Ayutthaya in 1351 with Ayutthaya its capital, sitting on an island surrounded by rivers. It grew rapidly into one of the most powerful states in Southeast Asia, through trade, military expansion and diplomacy.
Ayutthaya had extensive trade links with China, Japan, Persia and India.

King Trailok (1448 – 1488) centralised the Kingdom.
A series of wars were fought with Burmese kingdoms throughout the history of Ayutthaya and in 1569 Ayutthaya was captured by the Burmese Toungoo Empire.
King Naresuen the Great (1590 – 1605) restored Siamese independence, defeating Burma.
Following this, during the 17th century, Ayutthaya became one of the world’s largest cities, enjoying international trade from all ports. With King Narai the Great (1656 – 1688) expanding diplomatic relations with European powers (especially France) welcoming foreign merchants, diplomats and missionaries.

In 1767, Burmese armies once again invaded Ayutthaya, laying siege to the kingdom, before destroying it and bringing it to a complete end.

After the destruction of Ayutthaya, a general, Taksin, rallied surviving Siamese forces, they expelled the Burmese. A new capital was established at Thonburi, near modern Bangkok and much of the former Ayutthaya kingdom was reunited.
Taksin restored political stability and reasserted influence over neighbouring states, Cambodia and Laos included.
Despite his successes, Taskin’s military campaigns had grown exhausting on the aristocracy and subjects. Taskin himself had become increasingly erratic, he experienced religious delusions, believing himself to have reached the highest level of Buddhist spiritual enlightenment and flogging any Monks who disagreed.
In 1782 rebellion broke out in Thonburi, a campaigning General Chao Phraya Chakri, returned from Cambodia and quelled the rebellion. This however led to him becoming the dominant military figure in Siam and under his approval Taksin was removed from power, detained and then executed.

General Chao Phraya Chakri dubbed himself King Ram I and founded the Chakri Dynasty, establishing Bangkok as the capital.
Early Chakri kings focussed on rebuilding Siam after the devastation of the constant Burmese wars that had filled the centuries prior. Control over Laos and Cambodia was consolidated after the work of Taksin.
Through the 1800s Siam was modernised, and whilst Britain expanded into Burma and Malaya, and France expanded into Indochina, Siam remained independent. Becoming the only Southeast Asian nation to avoid full European colonisation. Although, to preserve independence, some territories were ceded to both Britain and France.

In 1917 Siam entered the First World War on the side of the Allies and gained international recognition, noted at the Treaty of Versailles.

A bloodless revolution ended pure monarchy and established a constitutional government in 1932. Then in 1939 Siam officially changed its name to Thailand.

During the Second World War, Thailand allied with Japan, following the Japanese invasion in 1941, though a resistance movement known as Seri Thai worked secretly, cooperating with the Allies.
Following the war, Thailand became a close ally of the US, receiving significant economic and military support. This bond grew as Thailand supported US anti-commnist efforts, hosting military bases during the Vietnam War.
Frequent military coups and military governments led to civil unrest.