I am currently listening to and greatly enjoying the incredibly well put together, insightful, and monumentally informed audiobook version of 'The Boundless Sea: A Human History of Oceans' by David Abulafia, and in Chapter 28 Part III, David notes the following:

The bodies of strange people had been cast up on the shores of Ireland, and their features were rather like those of Tartars. In other words, the 'Orientals' with whom Westerners were reasonably familiar through political contact and through the trade in slaves from the Black Sea into the Mediterranean. Almost certainly, these were the bodies of native North Americans which had been washed out to sea. If, as is possible, the young Columbus travelled to Iceland, he might well have heard tales of lands to the West visited by Norse sailors in the past. In Bristol, he could also have picked up rumors of lands to the West, because several Icelanders had taken up residence there, and because English expeditions had penetrated deep into the Atlantic in the 1480s. Besides, he seems to have read some mysterious papers in the possession of the Perestrelo family of Porto Santo near Madeira (into which he married) which provided further evidence of land to the West.18

As I am simply listening to the audiobook version and do not have access to specific sources, I am wondering if this is common knowledge, and/or known to historians as a matter of fact or likely probability?

Thank you to anyone able to illuminate this further. And, for anyone curious, I highly recommend this audiobook and have been addictively surprised by David Abulafia's ability to provide a nuanced perspective on thousands of pivotal historical events through the medium of oceanic exploration.