This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Buddhism reaches Sri Lanka around 247 BCE, when the Mauryan emperor Ashoka, having adopted the faith after his own conquest of Kalinga, sent a missionary embassy to the island. By most chronicle accounts the missionary was his own son Mahinda, who met the Sinhalese king Devanampiya Tissa at Mihintale near Anuradhapura and preached the Dhamma directly to him.
Mahinda's mission converted the king, and through the king's own patronage it converted a royal court, giving Buddhism the durable state backing that made Sri Lanka the tradition's oldest continuously documented home anywhere. His sister Sanghamitta carried the mission further, bringing a branch of the Bodhi tree to the island and founding its own order of nuns, so that Sri Lanka received not only the teaching but the living institutions needed to sustain it.
What changed for Buddhism's spread is the creation of an established center outside India itself, one whose own chronicles and ordination lineage would later carry the Theravada tradition onward into Southeast Asia. Sri Lanka's Buddhism is recorded here as established rather than merely arrived, the stronger of the spread status readings this atlas tracks, on the strength of that same durable royal patronage.