Buddhism in Sri Lanka is primarily of the Theravada school, and constitutes the religious faith of about 70% of the population.According to traditional Sri Lankan chronicles (such as the Dipavamsa), Buddhism was introduced into Sri Lanka in the 2nd century BCE by Venerable Mahinda, the son of the Emperor Ashoka, during the reign of Sri Lanka’s King Devanampiyatissa. 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 2nd 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 2000 years.
Divisions in the Buddhist clergy
The different sects of the Sri Lankan Buddhist clergy are referred to as Nikayas, and three main Nikayas are:
Siam Nikaya, founded in the 18th century by a Thai monk who perceived corruption in the sangha and attempted to purify its practices
Amarapura Nikaya, founded in 1800 with higher ordination obtained from Myanmar (Burma)
Ramanna Nikaya, founded in 1864 by Ambagahawatte Saranankara.
Within these three main divisions there are numerous other divisions, some of which are caste based. There are no doctrinal differences among any of them.