The Sukhothai Kingdom was a post-classical Siamese kingdom (maṇḍala) in Mainland Southeast Asia surrounding the ancient capital city of Sukhothai in present-day north-central Thailand. It evolved from a trading hub to a city-state in 1127 and emerged into the kingdom by Si Inthrathit in 1238. Sukhothai existed as an independent polity until 1438 when it fell under the influence of the neighboring Ayutthaya after the death of Borommapan (Maha Thammaracha IV).
Sukhothai is traditionally understood to have been established as a commercial hub within the Dvaravati Lavo in the 7th century. Following the decline of Lavo, the polity appears to have fallen under the suzerainty of the Qiān, whose authority was ultimately extinguished following their defeat by Angkor in 946 CE. After that, Sukhothai was subsequently incorporated into the domain of Haripuñjaya approximately a decade later. By the mid-12th century, control of the city was reasserted by the Xiān monarchs—a dynasty descended from the Qiān—who are believed to have maintained a brief period of subordination to Angkor between the late 12th and early 13th centuries. Sukhothai is conventionally regarded as having emerged as an independent polity in 1238 CE.