Initial states of Thailand
Prior to the southwards migration of the Tai people from Yunnan in the 10th century, the Indochina peninsula had been a home to various indigenous animistic communities for as far back as 500,000 years ago. The recent discovery of Homo erectus fossils such as Lampang man is but one example. The remains were first discovered during excavations in Lampang province, Thailand. The finds have been dated from roughly 1,000,000-500,000 years ago in the Pleistocene. There are myriad sites in Thailand dating to the Bronze (1500 BC-500 BC) and Iron Ages (500 BC-AD 500). The most thoroughly researched of these sites are located in the country's Northeast, especially in the Mun and Chi River valleys. The Mun River in particular is home to many 'moated' sites which comprise mounds surrounded by ditches and ramparts. The mounds contain evidence of prehistoric occupation.
Around the 1st century of the Christian era, according to Funan epigraphy and the records of Chinese historians (Coedes), a number of trading settlements of the South appear to have been organized into several Indianised states, among the earliest of which are believed to be Langkasuka and Tambralinga.
Ancient Civilizations
Prior to the arrival of the Tai people and culture into what is now Thailand, the region hosted a number of indigenous Mon-Khmer and Malay civilizations. Yet little is known about Thailand before the 13th century as the literary and concrete sources are scarce and most of the knowledge about this period is gleaned from archeological evidence.
Dvaravati
A 13 meter long reclining Buddha, Nakhon Ratchasima
The Chao Phraya valley in what is now Central Thailand had once been the home of Mon Dvaravati culture, which prevailed from the 7th century to the 10th century. The existence of the civilizations had long been forgotten by the Thai when Samuel Beal discovered the polity among the Chinese writings on Southeast Asia as “Tou-lo-po-ti”. During the early 20th century the archeologists led by George Coedès made grand excavations on what is now Nakorn Pathom and found it to be a center of Dvaravati culture. The constructed name Dvaravati was confirmed by a Sanskrit plate inscription containing the name “Dvaravati”.
Khmer period Thai sculpture of Vishnu, ~10th century
Later on, many more Dvaravati sites were discovered throughout the Chao Phraya valley. The two most important sites were Nakorn Pathom and Uthong (in the present Suphanburi Province). The inscriptions of Dvaravati were in Sanskrit and Mon using the script derived from the Pallava script of the Pallava dynasty. The religion of Dvaravati is thought to be Theravada through contacts with Sri Lanka, with the ruling class also participating in Hindu rites. The Dvaravati art, including the Buddha sculptures and stupas, showed strong similarities to those of the Gupta dynasty. The most prominent production of Dvaravati art are the Thammachakras or the Stone Wheels signifying Buddhist principles. The eastern parts of the Chao Phraya valley were subjected to a more Khmer and Hindu influence as the inscriptions are found in Khmer and Sanskrit.
Dvaravati was not a kingdom but a network of city-states paying tributes to more powerful ones according to the mandala model. Dvaravati culture expanded into Isan as well as southwards as far as the Isthmus of Kra. Dvaravati was a part of ancient international trade as Roman artifacts were also found and Dvaravati tributes to the Tang court are recorded. The culture came to an end around the 10th century when it was replaced by a more unified Lavo-Khmer polity.
Si Kottaboon
While the Dvaravatians ruled Chao Phraya, Isan was the place of the Si Kottaboon culture, which belonged to the native Mon-Khmer people. Si Kottaboon is regarded as a stem culture of Dvaravati with Mon scripts and oval-shaped cities. The Thammachakras of Dvaravati became the Semas or Stone Leaves of Si Kottaboon. The culture tolerated the Khmer Chenla expansions around the 7th century. The southeasternmost part of Isan was the heartland of the Chenla kingdom that expanded over the southern Funan around the 7th century.
Southern Thailand
Below the Isthmus of Kra was the place of Malay civilizations. Primordial Malay kingdoms are described as tributaries to Funan by 2nd century Chinese sources – though most of them proved to be tribal organizations instead of full-fledged kingdoms. From the 6th century onwards, two major mandalas ruled Southern Thailand – the Kanduli and the Langkasuka. Kanduli centered on what is now Surat Thani Province and Langasuka on Pattani. Southern Thailand was the center of Hinduism and Mahayana. The Tang dynasty monk I Ching stopped at Langkasuka to study Pali grammar and Mahayana during his journey to India around 800 AD. At that time, the kingdoms of Southern Thailand quickly fell under the influences of the Malay kingdom of Srivijaya from Sumatra.