describe the geological and geographical conditions that set the stage for North American history

225 million years ago Pangea started to break apart and 2 million years ago the "Great Ice Age" happened. The oceans became glaciers and sea levels dropped. The decrease in sea level exposed an Isthmus that connected Asia and North America. This isthmus, known as the Bering Isthmus, was used by Asian colonists to get across from Asia. These Asians developed into Native tribes that made the America's their home. The Bering Isthmus was covered when Ice began to melt and sea levels rose.