Who brought Buddhism to Sri Lanka?
The Sri Lankan chronicles, the Dīpavaṃsa (4th century CE) and the Mahāvaṃsa (5th to 6th century CE), give a clear answer. After the Third Council, the elder Mahinda, Ashoka's son, travelled to the island with a small group of monks. Later, his sister Saṅghamittā, Ashoka's daughter, followed with nuns.
Ashoka's role, in this account, was as a sender and an ally: he had already exchanged gifts and envoys with the Sri Lankan king. Ashoka's own inscriptions name Tambapaṃṇi, usually identified with Sri Lanka, among the places his envoys of dhamma reached, though they never name Mahinda.
Mahinda at Mihintale
The Mahāvaṃsa tells that on the full moon of the month of Poson, King Devānampiya Tissa was hunting deer on the hill now called Mihintale when a monk called him by name. It was Mahinda. To test the king's intelligence, Mahinda asked him a series of riddles about mango trees, then taught him. The king and his companions took refuge in the Buddha.
The king gave the Mahāmegha park in his capital, Anuradhapura, for a monastery. It became the Mahāvihāra, the centre of Sri Lankan Theravāda for more than a thousand years. The first stupa on the island, the Thūpārāma, was built nearby to hold a relic of the Buddha.
Saṅghamittā and the Bodhi tree
Princess Anulā, the wife of the king's brother, and many women of the court wished to be ordained, but only nuns could ordain them. So the king sent to Ashoka for Saṅghamittā. She arrived with a branch of the tree under which the Buddha awoke. Planted at Anuradhapura, it is revered today as the Jaya Śrī Mahā Bodhi and is often described as the oldest tree in the world planted by humans with a known date.
Why it matters
Sri Lanka becomes one of the most important centres for the preservation and development of Theravāda Buddhism, and the place where the Pāli teachings were later written down.
History and tradition
What historians can say
That Buddhism took root in Sri Lanka around the 3rd century BCE is supported by early Brāhmī inscriptions recording gifts of caves to monks, some of the oldest writing on the island. The details of Mahinda and Saṅghamittā come from the chronicles, written several centuries later. The Chinese pilgrim Xuanzang, visiting India in the 7th century, recorded a different tradition in which Mahendra was Ashoka's younger brother, not his son.
What Buddhist tradition remembers
The Mahāvaṃsa places Sri Lanka at the centre of the Buddha's own plans. It says he visited the island three times, and that on the day of his death he told Sakka, king of the gods, that his teaching would one day be established in Laṅkā, and asked him to protect the island. Poson, the June full moon, is still celebrated across Sri Lanka as the day Mahinda arrived.