What is an historical theory versus fact about ancient American civilization A people walked across the Bering Strait during the ice age B in the ice age the Bering Strait was above sea level?

For ancient American civilization, scientists speculate that people walked across the Bering Strait during the ice age. This would explain HOW Native Americans were on the North and South American continents long before the discovery of the New World. They base this theory on the fact that in the ice age the Bering Strait was above sea level.

An opposing theory might be that Native Americans were on the continent before Pangaea completely broke apart.