Perhaps. But neither one of them ever documented such “discoveries”. Seems to me like another attempt to delegitimize Columbus.
Perhaps?. The Icelandic sagas “Saga of the Greenlanders” and “Saga of Eric the Red” document “Vinland”. While there are some discrepancies between the two; the accuracy of these sagas was proven when they were used by archeologists to locate the Norse settlement at L’Anse Aux Meadows in Northern Newfoundland. This settlement only lasted about 8-10 years. It’s existence and the Sagas pretty well document the Norse discovery of the Americas 500 years before Columbus. However, I am not aware of any of this information ever being taken back to Europe.
... another attempt to delegitimize Columbus.
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Perhaps. But, no matter what may be learned about earlier “discoveries” of America, it was not until Columbus’s voyages that things really started poppin’. So they can’t take that away from him.