How was it possible for prehistoric to cross the bering strait?

All speculation: 1) It is commonly believed that humans were able to cross the Bering Strait because of low sea level due to the large amount of glacial ice. The exposed land allowed people and animals to travel from the continent of Asia to North America. 2)Another common belief is that humans were able to cross over the ice which was present at the time. This ice bridge has melted since then and ended the possibility of walking from one end to the other. I think this is the most feasible solution.