If I correctly understand what he is saying, the author doesn't accept OT scripture as textual evidence.
Genesis clearly indicates that all the earth's tribes are descended from Noah's three sons. The only way that could not be true would be if Noah's flood was merely a folk fable adopted by Moses to spice up his story, or was allegorical, or was literal but confined to a limited region, or was literal but Moses left out part of the story.
The Genesis flood account says it was both literal and universal, and I choose to believe divinely inspired holy scripture over any man's opinion no matter how learned he may be.
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