The significance of Bak poya is historical, since it marks Buddha’s second visit to Sri Lanka. This is noteworthy, as Bak is a month of national importance as well.
According to Mahavamsa, Buddha could foresee an imminent war between two Naga Kings Culodara and Mahodara, uncle and nephew, over a jewel-studded throne that made Him think of visiting Lanka for the second time. Professor Wilhelm Geiger explains the conflict in the translation of Mahavamsa:
“That same Naga Mahodara was then a King, gifted with miraculous power in a Naga Kingdom in the ocean, that covered half a thousand Yojanas. His younger sister had been given (in marriage) to the Naga-King on the Kannavaddhamana mountain; her son was Culodara. His mother’s father had given to his mother a splendid throne of jewels, then the Naga had died and therefore this war of nephew with uncle was threatening and also the Nagas of the mountains were armed with miraculous power.
Mahavamsa also records that the Buddha was accompanied by a deity to Sri Lanka.
“The deva named Samiddhisumana took a rajayatana-tree standing in Jetavana, his own fair habitation and holding it like a parasol over the conqueror, he with the Teacher’s leave, attended him to that spot where he had formerly dwelt. That very deva had been, in his latest birth, a man in Nagadipa.
On the spot where thereafter the rajayatana-tree stood, he saw paccekabuddhas taking their meal. And at the sight his heart was glad and he offered branches to cleanse the alms-bowl.
Therefore he was reborn in that tree in the pleasant Jetavans garden, and it (the tree) stood afterwards outside at the side of the gate-rampart. The God of all gods saw (in this) an advantage for that deva and for the sake of the good which should spring (therefrom) for our land, he brought him hither (to Lanka) together with his tree.
Mahavamsa then relates how Buddha settled the dispute and the next development of events.
“Hovering there in mid-air above battlefield the Master, who drives away (spiritual) darkness, called forth dread darkness over the Nagas. Then comforting those who were distressed by terror he once again spread light abroad.
When they saw the Blessed One they joyfully did reverence to the Master’s feet. Then preached the Vanquisher to them the doctrine that begets concord and both (Nagas) gladly gave up the throne to the Sage.
“When the Master, having alighted on the earth, had taken his place on a seat there and had been refreshed with celestial food and drink by the Naga-Kings, he the Lord, established in the (three) refuges and in the moral precepts eighty kotis of snake-spirits, dwellers in the ocean and on the mainland.
“The Naga-King Maniakkhika of Kalyani mother’s brother to the Naga Mahodara, who had come thither to take part in the battle and who, aforetime, at the Buddha’s first coming, having heard the true doctrine preached, had become established in the refuges and the moral duties, prayed now to the Tathagata: ‘Great is the compassion that thou hast [you have] shown us here, O Master!
Hadst thou [had you] not appeared we had all been consumed to ashes. May thy [your] compassion yet light also especially on me, O thou who art [are] rich in loving-kindness, in that thou shalt [shall] come again hither to my dwelling country, O thou peerless one’.
When the Buddha had consented by his silence to come thither [there], he planted the rajayatana-tree on that very spot as a sacred memorial and the Lord of the Worlds gave over the rajayatana-tree and the precious throne-seat to the Naga-Kings to do homage thereto. ‘In remembrance that I have used these do homage to them, ye Naga-Kings!”
Buddha’s calling forth dread darkness over the Nagas should not be misunderstood. The Buddha holds fame for being the Greatest Compassionate on earth. The concept bears a symbolic meaning; Buddha preached the dark side of the world, and the Naga tribes were scared just to hear and visualise them. That paved the way for them to a comfort later on.
Buddha’s visits to Sri Lanka are believed to be false and legendary in certain sects. One reason is that it is not contained in Thripitaka, the official document of Buddha’s life. Thripitaka contains more of philosophically important factors, rather than history. Buddha had been to Sri Lanka thrice: first visit to Mahiyangana, second to Jaffna, then called as Nagadipa, and third to Kelaniya.
The common question is that if Buddha had already been to Sri Lanka, not only once, but thrice, why did Arahant Mahinda visit Sri Lanka once again. Arahant Mahinda, of course, had a mission to fulfil: to establish the Upasampada Bhikku order. The suitable time was not ripe for Buddha to consider establishing the serious Bhikku order. However Buddhism was not alien when Arahant Mahinda set foot.