According to Mahawansa, the effect of Vijaya is enormous. It clearly say that we are descendants of Vijaya and the relationship with Native was not be that good. Possibly many native people moved to jungle. Some joined with Vijaya (possibly very little). After some time, indian immigrants control of the country and consolidate here and the pure native people restricted to Jungles.
Machan oya wijaya kuveni story gery suddha gothapu kathawak ban. mahanwashaya ehema sudda apita dala giya kathwak ban. un apiwa tamat manipulate karanawa apita terenne na.
Introduction to George Turnour’s edition of the Mahavansa
In the year 1826 an Englishman, the Hon. George Turnour (1799–1843), sat in his office in the Kachcheri buildings at Ratnapura in the Saffragam Province of Ceylon. Those were the days of Empire, full-blooded and confident. The Colonial Service, in particular, was attracting men of culture and high feeling, for whom the betterment of mankind in general, and not personal prosperity, was the principal objective.
George Turnour was one of these men, and history has shown him scant recognition, for his contribution to a fuller knowledge of the past must be considered unique.
http://mahavamsa.org/mahavamsa/original-version/