It seems that my precious posts on Prince Vijay Singha are lost again!
So here i go again, Sinhalese people are long distant cousins of Bengali people.
And here are the sources!
https://en.wikipedia.org/wiki/Prince_Vijaya
"Prince Vijaya (
Sinhala: විජය කුමරු) was the traditional first Sinhalese king of
Sri Lanka, mentioned in the
Pali chronicles, including
Mahavamsa. According to these chronicles, he is the first recorded King of Sri Lanka. His reign is traditionally dated to 543–505 BCE. According to the legends, he and several hundred of his followers came to Lanka after being expelled from an Indian kingdom"
Of course Vijay Singha was from Ancient Bengal. He had come to Srilanka 200 years before Alexnder came to India and Chandragupta Mayurya got an empire in India. Just some perspective.
Here genetic studies on Sinhalese:
https://en.wikipedia.org/wiki/Genetic_studies_on_Sinhalese
Tamils are distant in-laws of Bengali people of course. If someone looks at the map of Akhanda Bharat, he will realize that eastern indians are an ethinicity that has influence from North India(UP is closest to east India), Darjeeling/Sikkim/Tibet/NE of India (from here comes the mongoloid influence) and south India (AP is nearest to eastern India).