"His book 1421: The Year China Discovered the World, is a work of sheer fiction presented as revisionist history. Not a single document or artifact has been found to support his new claims on the supposed Ming naval expeditions beyond Africa."
I had a look into his book. It is not written very scientifically. From a review: "A true academic work would have been far more careful to distinguish between what is hard evidence and what is inference, assumption, and hypothesis."
Known by Europeans; it's been "known" / inhabited for at least 10.000 years. As far as I'm aware there's no records of other major players visiting / "discovering" it though besides the Norse.
