The great Mahaweli river was one of the favourite migrant routes of those settlers.
Consequently, this particular river valley became a significant religious, political and economical route cum boundary and haused a considerable number of large and small religious sites along the winding terrain.
Soon after flowing past the national Park associated with the sacred relic site of Somawathie, the river splits into two delta arms to reach the Bay of Bengal: the one flowing towards Koddiar bay at Trincomalee to continue as a major submarine canyon, making Trincomalee one of the finest deep sea harbors in the world, and the other flowing in a north-east direction past the sacred relic site of Seruvila, to reach the Ullackalie Lagoon located to the south-east of Trincomalee.
The river valleys were known routes for the settlers to migrate along.
Prince Vijaya from North India came in 5th century BC and met Princess Kuveni who belonged to an aboriginal clan in the island.
The pilgrim route commencing from Seruwila and running through Somawathie, Polonnaruwa, Mahiyangana, Kandy and ending at Sri Pada touches such significant enshrinments as those of the Frontal Bone relic, Right Tooth Relic, Hair Relic and the Gem studded chair, Left Tooth Relic and the Foot Print mark of the Great Master, the Lord Buddha.
According to text there had been three types of relics; the bodily remains of the Master, the objects of use or of wear attributed to the Master and his memorials.It is evident that the route was populated and utilized throughout the historical phase since pre Christian times due to the existence of Brahmi Inscriptions at nodal locations and consequent to the accounts left by Kings like Gotabhaya in the second century BC, discovery of Sacred Foot Print by King Valagamba in first century BC, Fa Hian in the fifth century, Kings Vijayabahu and Prakramabahu in eleventh and twelfth centuries, Marco Polo in thirteenth century, Al Beruni in the fourteenth century, Iban Batuta in the fourteenth century.