I am not a historian. Andaman and Nicobar (neighbor of Sentinelese) is occupied / use as naval base by outsiders for >1000 years. None of the Cholas, Europeans, Japan ever contacted/impacted them seems highly unlikely.
Contacts tended to be recorded. You can read ships logs now going back hundreds of years, often with illustrations. There's not a whole lot that happens in most ship voyages, so things like running into a weird group on an isolated island would absolutely have been recorded in immense detail. Of course I can't prove, beyond any question, that they weren't contacted, but there's 0 evidence to suggest they were, and immense evidence to suggest they were not. For the Nukak this is at least as true as well.
