My guess is quite a few people from Europe made it to America before Columbus. Except for the Vikings I doubt any of them made it back to Europe.
I have often read about early American explorers running into Indians who spoke various English dialects or maybe just knew a few words.
America B.C.A fascinating letter I received from a Shoshone Indian who had been traveling in the Basque country of Spain tells of his recognition of Shoshone words over there, including his own name, whose Shoshone meaning proved to match the meaning attached to a similar word by the modern Basques. Unfortunately I mislaid this interesting letter. If the Shoshone scholar who wrote to me should chance to see these words I hope he will forgive me and contact me again. The modern Basque settlers of Idaho may perhaps bring forth a linguist to investigate matters raised in this chapter. [p 173]
by Barry Fell
(1976) find it in a nearby library