In the first half of the 13th century two Thai princes in Sawankhalok and Sukhothai, outposts of the Khmer empire, succeeded in shaking off the Khmer yoke. The son of one of them, King Rama Khamheng, soon extended his rule over almost the whole of Thailand except for the northern provinces. The Theravada form of Buddhism, taken over from the Mons, increasingly gained ground in the state of Sukhothai. This development was furthered by Sinhalese monks whom Rama Khamheng brought in from Ceylon.
Although Sukhothai lost most of the conquered territories again soon after the death of its founder (the Kingdom became a vassal state of Ayutthaya in the second half of the 14th century, and was incorporated in it in the 15th), it nevertheless laid the foundations for the Thai domination of the country.
Impressive remains of Sukhothai architecture are preserved at Sukhothai and Si Satchanalai. The buildings of the period reflect a variety of influences; large, bell shaped stupas borne by elephants go back to Ceylonese models. In other cases the influence of Mon architecture is recognisable. From the Khmer tower sanctuary the Thai prang was developed. And yet, all these buildings are not mere imitations of foreign models. The Thais managed to vary the elements they adopted and adapt them to their own taste. Perhaps the most characteristic architectural form of the period is a tall slender chedi with a square base, surmounted by an onion shaped spire. The finest example of this is in Wat Mahathat at Sukhothai. All the buildings belonging to a wat occur here in their basic forms. The wiharn with brick walls and a tiled roof has the narrow slit windows which are typical of the Sukhothai and early Ayutthaya periods. Windows of this type are preserved in the wiharn of Wat Mahathat in Phitsanulok. The shafts of light admitted by these windows give the interior an atmosphere of peculiar solemnity.
A small building in Nakhon Sawan shows the simplest and most primitive form of wiharn. In more developed types the nave was flanked by two aisles, sometimes even by four or six. The roof was supported by rows of columns. The mondop, a cubic building with a pyramidal roof, is also frequently found, but often the roof has collapsed. Only the kuti (dwelling) of Phra Ruang at Si Satchanalai has retained its original form. Its affinity with Mon structures is evident. The usual building materials were laterite and brick. Ornamentation was carried out in plaster, and glazed ceramic decoration was also used.
The sculpture of this period is moulded, in contrast to that of the Khmers. Bronze for figures in the round and plaster for bas-reliefs were the favourite means of expression of the Thai artists. We know from an inscription in the name of Rama Khamheng that the Sukhothai school was already flourishing before the end of the 13th century. Production continued well into the 16th century: thousands of life-size and over life-size figures are preserved, as well as innumerable statuettes. Of all these sculptures, only five can be precisely dated by inscriptions on the base: three standing and one walking Buddha cast at Nan in 1426 and a seated Buddha of unknown origin, dated to the year 1422, now in Wat Hong in Dhonburi.
The artists of the Sukhothai period (unlike those, for instance, of U-Thong) depicted Gautama in the state of full Enlightenment, as the Buddha. The transfigured mind and spirit are indicated by the completely relaxed muscles and peaceful features. The aim of this art is never to present a portrait, but to make spiritual qualities visible. This explains the softlines of the body, which seem slightly feminine to the western eye. The best works of the period are distinguished by the expressive heads and the fine modelling of the hands. Their high artistic quality was never afterwards surpassed, and the Sukhothai style is rightly regarded as the classical period of Thai art. Almost all the figures show the Buddha seated with one leg over the other and, with few exceptions, the right hand pointing to the ground (bhumisparsha-mudra). The most famous bronze Buddha of this period is the Phra Buddha Jinaraja in Phitsanulok, of which there is a copy, the same size as original, in Wat Benchamabopit in Bangkok. A characteristic feature of the period is the flowing, curved contour. Few examples of the reclining Buddha are found from this period, but a fine specimen is to be seen in Wat Bovornivet in Bangkok.
On the walls of the temples in Sukhothai, particularly Wat Mahathat, some remarkable plaster reliefs are preserved. The relief of the “descent from the heavens” in Wat Trapang Tong Lang is one of the finest works of Buddhist art. The Buddha is shown descending from heaven on the mythical. staircase, surrounded by adoring deities, while Indra and Brahma hold umbrellas over his head. Only a few traces remain of the gilding and colouring.
In Sukhothai, too, we meet for the first time the “footprints of the Buddha”. Legend relates that the Buddha left his footprint on Adam’s Peak in Ceylon as a sign that his religion was flourishing in that country. The Kings of Sukhothai, we learn from old inscriptions, had casts of this footprint brought to their country and set up in the neighbourhood of their capital in order to bear witness to the establishment of the Buddhist faith in their country. These footprints show symbolically, in 108 signs, the omniscience of the Buddha higher heavens with their gods, six lower heavens with their minor deities, the earth with Mount Meru, surrounded by the seven seas, the four great continents with their islands, the seven great rivers and lakes, animals and plants of good omen, the insignia of a rightful King and the ritual requisites of the monks. All this can be seen in detail in Wat Phra Jetubon (Wat Po) in Bangkok.