According to traditional Sri Lankan chronicles (such as the Dipavamsa); Buddhism was introduced into Sri Lanka in the 4th century BCE by Venerable Mahinda; the son of the Emperor Ashoka; during the reign of Sri Lanka's King Devanampiya Tissa. During this time; a sapling of the Bodhi Tree was brought to Sri Lanka and the first monasteries were established under the sponsorship of the Sri Lankan king. The Pali Canon; having previously been preserved as an oral tradition; was first committed to writing in Sri Lanka around 30 BCE.

Sri Lanka has the longest continuous history of Buddhism of any Buddhist nation; with the Sangha having existed in a largely unbroken lineage since its introduction in the 4th century. During periods of decline; the Sri Lankan monastic lineage was revived through contact with Myanmar and Thailand. Periods of Mahayana influence; as well as official neglect under colonial rule; created great challenges for Theravada Buddhist institutions in Sri Lanka; but repeated revivals and resurgences - most recently in the 19th century CE - have kept the Theravada tradition alive for over 2;600 years.