noun: The Bering land bridge, a geographical phenomenon roughly 1,000 miles (1,600 km) wide (north to south) at its greatest extent, which joined present-day Alaska and eastern Siberia at various times during the Pleistocene ice ages; the land bridge previously occupying what is now the Bering Strait.
noun: All the land between the Lena river in Russia and the Mackenzie river in Canada
