MAP 1.1 The Wisconsin Glaciation and the Settling of the Americas In roughly 16,000 B.C.E., ice covered most of North America. Its presence lowered the depth of the world’s oceans, creating a land bridge called Beringia between Siberia and Alaska. Asian peoples likely migrated to North America across this bridge, hunting woolly mammoths and other game, and then slowly moved south and east as the ice retreated over the next four thousand years.