Tun Sun

Tun Sun (Chinese: 頓遜) or Tian-Sun or Tien-Sun (Chinese: 典遜; Thai: เทียนสน) or Tu-k'un/Tou-k'ouen/Ch'u-tu-k'un (都昆), was a group of five ancient Mon political entities, stretching from present-day lower central Thailand to the Kra Isthmus in southern Thailand and Tanintharyi Region of Myanmar. It existed from the 1st to 6th centuries CE, and was said to have stretched from the east to the west coast, controlling a vital branch of long-distance maritime trade between the India Ocean and the South China Sea. It was also one of the earliest Indianized-states in Southeast Asia.

In the late 1st century, Tun Sun once vassalized its southern neighbor, Gē Luó Fù Shā (哥羅富沙), later known as Kamalanka), on the Kra Isthmus and Bandon Bay area, as mentioned in the Guangdong Tongzhi. Tun Sun remained independent until it was seized and became a vassal of Funan in the 3rd century CE, at least before 245 CE. Tun Sun disappeared from history about the beginning of the 6th century CE, when new principalities of Dvaravati emerged in central Thailand. Kamalanka or Lang-ya-hsiu, centered at the ancient Nakhon Pathom, was expected to be the successor of Tun Sun.

Roland Braddell proposed that an ancient emporium mentioned in the Geōgraphikē Hyphēgēsis of Ptolemy and the Buddhist texts, Mahāniddesa and Milinda Panha, in the 2nd–4th centuries, was one of the principalities in Tun Sun. The others four kingdoms of Tun Sun might be the vassalized Gē Luó Fù Shā, as cited in the Guangdong Tongzhi, and the three brothers of Gē Luó Shě Fēn (哥罗舍分国; Kamalanka), Xiū Luó Fēn, and Gān Bì (甘毕), as it was said to be situated in western Menam Valleys to the west of Dvaravati, where the three significant historical towns of the ancient Nakhon Pathom, Khu Bua, and Mueang Uthong are located.