Answer:
There once was a land bridge that connected Asia and North America some 15-20,000ish years ago that was used during the ice age. This ice bridge connected from what I believe to be eastern Russia (somewhere around that area) to westerm Alaska that helped the migration from Asia to North America and from North America to Asia. With the rise of sea levels and melted glaciers the land bridge basically drowned and melted never to be seen or used again.
