History:

Bhaduri: This surnames widespread distribution likely reflects historical migrations, both forced and voluntary. Forced movements, maybe due to political trouble or poverty, scattered families with this surname to new places. Seeking safety or better lives, they started new communities, keeping their name. Voluntary moves, like for trade, religion, or better land, also mattered. Over time, these movements, plus marriage and other things, changed where this surname is found and maybe even how its spelled or said.

Description:

Bhaduri: This surname is mainly found among Bengali Brahmins. Its connected to particular groups within that community, but figuring out the exact ones needs more digging into family history. Slight spelling and pronunciation changes across Bengal hint at different family branches and how they moved around historically.

These are educated guesses based on how names often change.