Festival celebrated in Sri Lanka on the full moon of June. The Poson Poya, which is specially noteworthy to the Sri Lankan Buddhists as the day on which Emperor Asoka’s son, the arahant Mahinda, officially introduced Buddhism to the island in the 3rd century B.C.
In addition to the normal ritualistic observances undertaken on a poya day, on Poson day devotees flock to Anuradhapura, the ancient capital city of the country, for it was there that arahant Mahinda converted the then ruler, King Devanampiya Tissa, and his court to Buddhism, thereby setting in motion a series of events that finally made Sri Lanka the home of Theravada Buddhism.
Even today, on Poson Poya, Anuradhapura becomes the center of Buddhist activity. Mihintale, the spot where the momentous encounter between the Elder and the King took place, accordingly receives the reverential attention of the devotees.
The two rituals of pilgrimage and the observance of the Eight Precepts are combined here. Processions commemorative of the event, referred to as Mihindu Peraheras, are held in various parts of the country.