Si Thep (Thai: ศรีเทพ, pronounced [sǐː tʰêːp]) is the southernmost district (amphoe) of Phetchabun province, Thailand, in the valley of the Pa Sak River.

[3] The ancient city of Si Thep was built in the Dvaravati era.

[4] Prince Damrong found the area of the old city in 1905 when he visited Monthon Phetchabun.

Si Thep is on a dry highland surrounded by waterways and floodplains bordered by mountains on both sides.

To ensure sufficient water for city use, ancient Si Thep had an elaborate system of ponds, tank moats, and a hydraulic system to bring water from higher grounds to sustain the city.