Nakhon Si Thammarat is one of the southern provinces of Thailand, on the eastern shore of the Gulf of Thailand. Neighboring provinces of Nakhon Si Thammarat include Songkhla, Phatthalung, Surat Thani and Trang, Krabi. The area around Nakhon Si Thammarat was even part of the center of the Srivijaya kingdom in the 3rd century. The Ramkhamhaeng stele lists the areas within the field of Sukhothai. After the fall of Sukhothai fell to his successor and the kingdom of Ayutthaya was one of the kingdoms tributary or 1st class provinces.

Nakhon Si Thammarat province is in southern Thailand. The name of the province derives from its Pali-Sanskrit name Nagara Sri Dhammaraja (City of the Sacred Dharma King), or Bandar Sri Dharma Raja in Malay, Thai, which becomes pronounced in Nakhon Si Thammarat. With the administrative reform thesaphiban the kingdom was more closely integrated into the state of Thailand and formed the Monthon Nakhon Si Thammarat. With the abolition of the system monthon in 1932, the province that covers only the central part of the former kingdom became the top-level administrative subdivision of Thailand.