Sukhothai, the first Thai kingdom, was founded around 1238 in the central part of present-day Thailand. In previous centuries, this area was under the sovereignty of Khmer kings who practiced Hinduism and MahĀyĀna Buddhism. The Thai, however, adopted TheravĀda Buddhism from Sri Lanka. Upon his return from Sri Lanka in the early 1330s, Si Satha, a high-ranking monk, introduced a new Sinhalese sect along with Buddha relics and artisans. The veneration of relics played a significant role in this sect, which dramatically transformed the architecture and plans of temple compounds. While earlier stŪpas (Thai, chedi) in Sukhothai were in Khmer-tower form (prang; e.g., Wat Phraphai Luang), new innovative forms were built after 1340 as stūpas became the religious and ceremonial centers of monasteries.
The most important temple remains that reflect the development of Sukhothai architecture are at Wat Mahathat (Monastery of the Great Relic), located in the center of the city. Wat Mahathat was built during King Ramkhamhaeng's reign (ca. 1279–1298) and was renovated around 1340 during the reign of the pious King Loëthai (1298–1346/7). Many forms of stūpas can still be seen (Khmer-tower, lotus-bud, and bell-shaped types), as well as the ruins of the congregational hall (ubosot or bot) and an assembly hall (wihan). A unique Sukhothai-type of stūpa was built on a low pyramidal platform of three levels that supported a staggered shaft that housed the relic. Above it was a smoothly rounded ovoid bulb (lotus-bud stūpa), which would later be crowned with a spire. Eight subsidiary stūpas were linked to the center with connecting walls. The four axial towers built in Khmer style were decorated with stucco designs similar to those on the Lankatilaka Temple in Sri Lanka, dating to 1342. Themes from the historical Buddha's past lives, meant to inspire practitioners, decorated the Mahathat tympana.
Ubosot and wihan were commonly built of brick covered with plaster and decorated with stucco. Their roofs were made of wood covered with ceramic tiles; for the most part, only the columns stand today. Ubosot can be distinguished from wihan by the (typically eight) boundary stones (sema) that were generally placed around it.
Griswold, Alexander B. Towards a History of Sukhothai Art. Bangkok: Fine Arts Department of Thailand, 1967.