So what. We know Vikings discovered North America before Columbus. But it was of little consequence.
Same thing with China. So what if they discovered it. If they did, they thought it was a worthless discovery.
It's like finding out Plato discovered relativity and then didn't tell anybody.
Actually, the Vikings major explorations were in invading and conquering the towns and villages along the river trading lines in what is commonly called RUSSIA.
That continent was named that because of these RED NORSEMEN who came along like they were trading, while exploring and INVADING.
RUSSIA is derived from a Word used by the original peoples that were living in what eventually became RUSSIA.
Protagoras discovered string theory and Plato covered it up.