The town, Chai Nat (ชัยนาท) is the provincial capital of Chai Nat Province, in the central region of Thailand.
Chai Nat means a roaring victory. Originally this ancient town was on the right bank of the Chao Phraya River at the mouth of Khlong Phraek Si Racha south of the old waterway. Established after the town of Phanthumwadi (Suphanburi Province), Chai Nat was Sukhothai's most important southern outpost built during the reign of King Phaya Loethai of Sukhothai during 1317–1336. This ancient community was called Mueang Phraek or Mueang San. When the Sukhothai Kingdom declined, Phraek became Ayutthaya's northern outpost. Later, a new community was established not far from Phraek. Its ruler was Chao Sam Phraya, who later ruled Ayutthaya and became King Borom Rachathirat II. This new community was a large town called Chai Nat. In the reign of King Rama V, the main settlement of the province in Laem Yang was moved to the left bank of the Chao Phraya River. Mueang San slowly declined because most of the people migrated to Chai Nat. The old town later became a district of Chai Nat. Chai Nat was an important military base to confront with the Burmese armies. As all these confrontations were successful, the city gained the name Chai Nat.