The Mon house

Two of the most important immigrant groups in Thailand were Khmers and Mons who arrived around the first century B.C., probably from southern China. Their culture would have a major impact on the subsequent development of Thai culture. The Khmers settled and area south of the northeast plateau deep into presen-day Kampuchea where their culture culminated in the mannificent 11th and 12th and century Angkorian civilization.
The Mons settled the western half of the lush Chao Phraya River valley and founded the Dvaravati kingdom which, besides being a major producer of rice, became and important religious center. The Mon seat of power was in the Nakhon Pathom area where various Buddhist artefacts have been discovered, and the remains of Buddhist monuments abound. Lop Buri, another Mon city, would remain a religious center after Thai Kingdoms became Buddhist during the 13th century. Another migration were during the Dvaravati period brought Tibeto-Burmese people into the area where, today, they from the itinerant hilltribes inhabiting the northern Thai mountains.

The counter-theory holds that the Thais orginated in Thailand and were driven northward by numerically superior Khmers and Mons. There, in Yunnan, the Thais developed their own distinctive culture. Later, under pressure from China's 11th and 12th century Mongolian conquerors, the Thais moved steadily southward again. Half of them, the Thai Yai (greater Thai) traveled across southern China to settle on Hainan island. The rest, the Thai Noi (lesser Thai) slowly moved directly southward to fill the vacuum left by the Khmers and Mon empires' decline.
Certainly by the 13th century, the Thais, in the fourth and final major immigration tide into Thailand, had successfully established themselves among the Khmers and Mons and had a firm foot-hood in the north. Bringing with them the advanced rice technology they had developed in Nanchao, the Thais industriously built extensive dikes and irrigation systems to transform fetid marshes into green rice fields. Their Chinese connections provided markets for surplus rice and enabled them to import Chinese inventions and implements to strengthen their own culture.

Paddle boat wait for merchandise
Ethnic identity of the Mons in Thailand
Gallery of Ko Kret (Kret Island) Map

: Tourism Authority of Thailand Tourist Service Center
: Hotel & Bungalows in Nonthaburi : Thailand in the 80s, Published by the National Identity Office, Office of the Prime Minister, Thailand, P. 13-15.