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

Dvaravati

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”.
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.