After the Kalinga War, the Mauryan emperor Aśoka promoted dhamma (moral law) and publicly supported Buddhist institutions. This new imperial policy created resources and political cover for long-distance religious networks, including missions beyond the subcontinent.
In Rock Edict XIII, Aśoka lists places where his policy of spreading dhamma reached, including “Tambapaṇṇi,” widely identified with Sri Lanka in later Buddhist tradition. The edict shows that Mauryan rulers publicly imagined influence extending across the Indian Ocean, even if the exact details of missions are debated.
Sri Lankan tradition says the monk Mahinda led a mission that encountered King Devanampiya Tissa near Anurādhapura at Mihintale and preached Buddhism to him. This encounter is treated as the turning point that brought royal sponsorship to Buddhism on the island, helping it become a lasting public religion.
Later Buddhist histories describe a “Third Buddhist Council” at Pāṭaliputra under Aśoka, associated with clarifying doctrine and organizing missionary activity. While historians debate the council’s precise history, the tradition is important because it frames Buddhist expansion as a coordinated, state-supported effort.
After the king’s conversion, a royal park at Anurādhapura (Mahamegha/Mahāmeghavana) was donated to the monastic community, and the Mahāvihāra monastery was established. This created a stable institutional base for Theravāda monastic education and textual transmission in Sri Lanka.
Sri Lankan accounts connect early stupas—especially Thuparama at Anurādhapura—with the first generation of Buddhist establishment under King Tissa. Stupas served as focal points for lay worship and helped make Buddhism visible in the city’s public landscape, not only in monasteries.
Tradition holds that Saṅghamittā arrived with a cutting from the Bodhi tree at Bodh Gayā, and it was ceremonially planted at Anurādhapura. The Bodhi-tree cult became a powerful symbol tying Sri Lankan Buddhism to key sites in India and strengthening the legitimacy of the new religion on the island.
With sustained royal backing, Anurādhapura developed into a major political and religious center for many centuries. Its monasteries, stupas, and pilgrimage sites helped Sri Lanka become a hub for Theravāda learning, with influence that could travel along trade routes to Southeast Asia.
Over the early centuries CE, Indian Ocean routes linked eastern India, Sri Lanka, and ports around the Bay of Bengal with mainland Southeast Asia. These commercial connections provided practical channels for monks, texts, and ideas, helping Buddhism move beyond royal missions into broader regional exchange.
Archaeology at the Pyu city of Sri Ksetra (in present-day Myanmar) documents flourishing urban life and Indic religious influences in the first millennium CE, with strong evidence by the 5th–7th centuries. This marks one of the clearer early Southeast Asian settings where Buddhism took root in an organized, city-based culture.
In the 5th century CE, the scholar-monk Buddhaghosa worked in Sri Lanka and wrote the Visuddhimagga (“Path of Purification”), a major synthesis of Theravāda practice and doctrine. Texts like this helped standardize teachings in Sri Lanka and supported the spread of shared Theravāda frameworks across the region.
By around the 5th century CE, Sri Lanka had durable institutions—monasteries, pilgrimage sites, and authoritative scholarship—that anchored Theravāda Buddhism for the long term. From this base, Buddhist ideas and styles could circulate across the Bay of Bengal alongside trade and diplomacy, shaping early Buddhist developments in parts of Southeast Asia.
Spread of Buddhism to Sri Lanka and Southeast Asia under Mauryan Patronage (c.3rd century BCE–5th century CE)