Chaiya (Thai: ไชยา, pronounced [tɕʰāj.jāː]) is a former capital district (Amphoe mueang) of Surat Thani province, Southern Thailand.

To the east is the Gulf of Thailand, with Cape Sui marking the northern end of the Bandon Bay.

Tang dynasty (7th–10th centuries) ceramics have been found in the area as well as pottery from India and glassware from Persia.

Similar finds have been made in Ban Thung Tuek, Takua Pa district, Phang Nga province on the other side of the isthmus, 200 km distant, indicating that there may have been an overland route connecting the Gulf of Thailand with the Andaman Seacoast.

Dated to the year 697 of the Mahasakkarat era (i.e., 775 CE), the inscription on a Bai Sema shaped stone tells about the King of Srivijaya having erected three stupas at that site and possibly the one at Wat Phra Borom That.