Beringia was a vast landmass that connected Asia and North America during the last ice age, spanning from northeastern Siberia across what is now the Bering Strait to western Alaska and Canada’s Yukon Territory. Far from a narrow bridge, it was a wide, treeless plain that served as both a self-contained ecosystem and the pathway humans used to first reach the Americas.
How the Land Bridge Formed
During ice ages, enormous volumes of ocean water became locked in continental ice sheets, and global sea levels dropped dramatically. At their lowest point during the Last Glacial Maximum (roughly 26,500 to 19,000 years ago), sea levels fell about 130 meters (around 425 feet) below where they sit today. The Bering Strait between Alaska and Russia is shallow, so even a modest drop in sea level exposed a wide stretch of dry land connecting the two continents.
Recent geochemical analysis published in the Proceedings of the National Academy of Sciences has refined the timeline considerably. The Bering Strait remained flooded until about 36,000 years ago, meaning the land bridge formed roughly 10,000 years before the coldest point of the last ice age. That’s later than scientists previously assumed. The terrestrial connection then persisted through the glacial maximum and didn’t disappear until rising seas flooded the strait again between 13,000 and 11,000 years ago.
A Dry, Treeless Grassland
Beringia looked nothing like the soggy, moss-covered tundra that covers much of the Arctic today. It was an arid grassland, sometimes called the “mammoth steppe,” characterized by low-growing, deep-rooted herbs and grasses under frequently clear skies. There were virtually no standing lakes, trees, or bogs. Rivers shrank to streams. Wind-blown silt created loess sheets and dune fields, and the skies were often dusty.
The key reason for this extreme dryness was simple geography. Falling sea levels pushed the Arctic Ocean coastline hundreds of kilometers to the north, and the massive ice sheet covering northern Europe blocked moisture flowing in from the west. The result was a condition called cryo-aridity: bitterly cold air that carried almost no moisture. This same lack of moisture explains one of Beringia’s most paradoxical features. While nearly all other land above the Arctic Circle was buried under glaciers, Beringia stayed ice-free. Mountains in the region exceeding 1,900 meters in elevation had no glaciers at all, because there simply wasn’t enough snowfall to build them.
The Animals of Beringia
The dry steppe supported a surprisingly diverse community of large mammals. Woolly mammoths, steppe bison, and several species of wild horse grazed the grasslands. Moose and wapiti (elk) browsed the scattered shrubs. Ground squirrels burrowed into the deep permafrost, and their ancient nests, preserved in the frozen ground, have given researchers a detailed window into the vegetation of the time.
As the climate warmed after the glacial maximum, the mammoth steppe began to shrink. Wetter conditions allowed shrubs and eventually wet tundra to replace the grasslands. Grazers like mammoths, bison, and horses lost habitat and declined toward extinction. Moose populations, by contrast, expanded rapidly around 14,000 years ago as increased moisture created more of the woody browse they depend on. Beringia was not just a transit corridor for these animals. It was a functioning ecosystem where species evolved, adapted, and eventually disappeared as conditions changed.
The Beringian Standstill
Beringia’s most consequential role may have been as a long-term home for the people who eventually populated the Americas. Genetic studies of Native American populations reveal a striking pattern: the mitochondrial DNA and Y-chromosome lineages found in Indigenous peoples across North and South America are largely unique, with no close matches found anywhere else in the world. These lineages have an evolutionary age ranging from about 13,000 to 22,000 years, meaning they developed during a prolonged period of genetic isolation.
This evidence supports what geneticists call the Beringian Standstill hypothesis. Rather than walking straight from Asia into the Americas, the ancestors of Native Americans appear to have lived in Beringia as a relatively isolated population for thousands of years. Estimates of how long this standstill lasted vary depending on the method. Some studies suggest as few as 2,400 years, others as many as 9,000, with a commonly cited middle estimate of about 5,000 years. During that time, the population developed its own distinct genetic signature, separated from East Asian populations by distance and from the Americas by the massive ice sheets that blocked southward travel.
Around 15,000 years ago, as ice sheets retreated and coastal or interior corridors opened, these Beringian populations expanded into the Americas. That expansion seeded the genetic foundation of all Indigenous peoples across two continents.
Archaeological Evidence in the Caves
Physical proof of this early human presence comes from Bluefish Caves in Canada’s Yukon Territory, one of the oldest known archaeological sites in North America. Researchers have identified animal bones bearing unmistakable cut marks from stone tools: straight, V-shaped incisions made during butchering and meat removal. The marked bones come from horses, caribou, wapiti, and possibly Dall sheep and bison.
The oldest of these specimens is a horse jawbone with cut marks from tongue removal, radiocarbon dated to about 24,000 calendar years before present, placing humans in the region during the Last Glacial Maximum itself. Additional cut-marked bones from the caves span from roughly 22,000 to 12,000 years ago, showing continuous or repeated human use of the area across more than 10,000 years. Stone tool assemblages found alongside the bones include microblades, specialized cores, and burins, the kind of small, precise tools suited to processing meat and hide in an Arctic environment.
What Remains Today
When sea levels rose and the Bering Strait flooded for the last time around 11,000 years ago, Beringia disappeared beneath roughly 50 meters of water at its shallowest point. Today the strait is only about 85 kilometers wide, and on clear days you can see Russia from Alaska’s western coast. The landscape on both sides still holds traces of its ice age past. In western Alaska, the Bering Land Bridge National Preserve protects a stretch of terrain that formed the eastern edge of Beringia. The preserve contains volcanic remnants, including lava flows, calderas, and maar lakes (craters formed by volcanic explosions through permafrost), along with hot springs that hint at the geologic forces still active beneath the surface.
Beneath the Bering and Chukchi Seas, the submerged plain is remarkably flat, a reminder that this was once open, walkable ground. Sediment cores pulled from the shallow seabed continue to yield pollen, insect remains, and other biological material that fills in the picture of what Beringia looked like when it was above water.