Why may have people crossed into North America to Siberia according to the land bridge theory?

According to the land bridge theory, people may have crossed into North America from Siberia via a land bridge called Beringia, which connected the two continents during the last Ice Age when sea levels were lower. This migration was likely driven by the search for food and resources, as people followed herds of large game animals that roamed the region. The land bridge provided a temporary route for these early hunter-gatherers, allowing them to expand into new territories.