Most of the theories claiming that various civilizations reached America before the vikings are generally considered bs. Given the fact that the minoans were an eastern Mediterranean civilization with no reason to make the near suicidal journey across the Atlantic ocean, it sounds pretty silly. Vikings got there and theres some evidence that European fishermen saw America before columbus. I've also heard the polinesians might have gotten to western south America, but I don't think were sure about anything other than Columbus and the vikings.