important : Singapor got independance 15 years after us.as soon as they got it they start building togather not trying to find who came first and who came last.now they've succeeded.
we soon after independance started to analyse who came first and who came last..but i guess still not finished with it.
just like sinhalese have the reasons for what they state,tamils muslims and burgers have thiers.
undeniable fact is who ever got leagal citizenship to this country should live in this country. doesnt matter he was born here, came her or fell from the sky.
if this bloody history only teaches that its our land others dont belong here its bull s*** and will never let a unity come and let the country develope.
funniest part is we are so proud that we kicked english (but even that mostly thanks to indian independant struggle..)and got independance and singapore din do a fight at all.use the brain first, thats why it has been put there..
ppl in this country dont want to fight to develope this country using brain. they want fight each other based on history that they proud of that has done nothing turned things backwords..

ok if you think this is off topic sorry, but it just comes with it.

and for your question, when two countries meet cultures get mixed up. im sure from the time ppl inhabited south india it effected sri lanka as well.and so called "pure" sinhalese culture itself has taken a lot from it (of course it has given back as well...)