Beringia and the Bering Land Bridge

Beringia is the region that links northeastern Asia and northwestern North America, including the Bering and Chukchi seas, the Bering Strait, the Chukchi and Kamchatka peninsulas, Alaska and the Yukon. During the last ice age, falling sea levels exposed a vast land bridge across the shallow Bering Strait, which at its widest reached about 1,000 kilometers north to south and covered roughly 1.6 million square kilometers. This corridor allowed plants, animals and, eventually, people to move between the continents [1].

Geography and Boundaries

Geographers define Beringia as stretching from the Lena River in Russia in the west to the Mackenzie River in Canada in the east, and from 72 degrees north in the Chukchi Sea to the tip of the Kamchatka Peninsula in the south. Today the central area is submerged, but its former uplands remain visible as the Diomede Islands, the Pribilof Islands of St. Paul and St. George, St. Lawrence Island, St. Matthew Island and King Island [1].

How the Land Bridge Formed

The Bering Strait averages only 40 to 50 meters deep, so the seabed became dry land whenever global sea level fell more than about 50 meters below its present level. Scientists describe a sequence in which a seaway existed from roughly 135,000 to 70,000 years ago, a land bridge from about 70,000 to 60,000 years ago, an intermittent connection from 60,000 to 30,000 years ago, and a continuous land bridge from about 30,000 to 11,000 years ago [1].

Continental ice sheets advanced from about 33,000 years ago and peaked near 26,500 years ago. Deglaciation began around 19,000 years ago, and rising seas flooded the bridge about 11,000 years ago. Post-glacial rebound continues to raise some coastal sections today [1].

Climate and Vegetation

Beringia was not covered by large ice sheets. It was a cold, dry steppe-tundra, an extension of the mammoth steppe that stretched across Eurasia. It received more moisture from the North Pacific than surrounding areas, supporting patches of shrub tundra and refugia of larch, spruce, birch and alder. During the last glacial maximum summers averaged 3 to 5 degrees Celsius cooler than today, with western Beringia in Siberia colder and drier than eastern Beringia in Alaska and the Yukon [1].

Animals of Beringia

The region supported one of the largest and most diverse communities of large mammals of its time. Woolly mammoths, saiga antelope and horses crossed the bridge freely, while the woolly rhinoceros stayed west of the Anadyr River in Siberia, and species such as the short-faced bear, American badger, Bootherium and Camelops were restricted to North America. Grey wolves also passed through a species-wide population bottleneck about 25,000 years ago before expanding from a Beringian refuge [1]. The woolly mammoth later became Alaska’s state fossil.

Human Migration

Genetic and archaeological evidence suggests that a small population of at most a few thousand people moved from eastern Siberia into Beringia during the last glacial maximum. People entered the Americas before 23,000 to 21,000 years ago as glaciers blocking the way south began to melt, and populations occupied both North and South America no later than 14,000 years ago [1][2].

The genome of an infant from the Upward Sun River site in Alaska, dated to about 11,500 years ago, defines the Ancient Beringian lineage, which split from the ancestral Native American lineage about 20,000 years ago. That ancestral population formed 20,000 to 25,000 years ago from a mix of about 65 percent East Asian and 35 percent Ancient North Eurasian ancestry [1].

After the Land Bridge

Rising seas separated the continents again, but people continued to move across the strait by boat and ice. About 3,000 years ago the ancestors of the Yupik peoples settled on both sides of the strait [1]. Alaska Native peoples such as the Iñupiat, Yupik and Unangax̂ are descended from later movements across the region [2].

Protected Heritage

In 2012 the United States and Russia announced plans for a transboundary area of shared Beringian heritage. In Alaska, the partner sites are Bering Land Bridge National Preserve and Cape Krusenstern National Monument, and in Russia Beringia National Park [1][3].

Ice Sheets and the Corridor South

The land bridge by itself did not open the interior of North America, because large ice sheets blocked the route. The Laurentide and Cordilleran ice sheets merged between about 24,000 and 13,000 years ago, a period when the continent south of Beringia was largely cut off by ice. Around 13,000 years ago a corridor through the Yukon opened, and it closed again around 10,000 years ago as seas rose and the climate changed [1]. Because of this timing, researchers have long debated whether early peoples traveled south along the Pacific coast, through the interior corridor, or by both routes. The timeline of the ice sheets also helps explain why gene flow between Beringian and North American populations varied through time [1].

The Beringian Gap Hypothesis

Biologists have noticed that some animals did not cross the bridge even when it was open. One explanation, called the Beringian Gap hypothesis, proposes an unconfirmed geographic or environmental factor that blocked or slowed migration across the bridge when it emerged. The idea would help explain why the woolly rhinoceros stayed in Siberia while mammoths, saiga antelope and horses spread across the region [1]. Another feature of Beringia is its east-west contrast: eastern Beringia in Alaska and the Yukon was more ecologically diverse than the colder and drier west, and from about 57,000 years ago steppe-tundra dominated the whole region. In Chukotka, the period from about 57,000 to 15,000 years ago was wetter and colder than the surrounding steppe-tundra, with warming beginning about 15,000 years ago [1].

FAQs

What is Beringia? Beringia is the region that connects Siberia and Alaska, including the land bridge exposed when sea levels dropped during the ice ages.

When did the Bering land bridge exist? The most recent continuous bridge existed from about 30,000 to 11,000 years ago, according to the sea-level sequence summarized by Wikipedia.

How wide was the land bridge? At its greatest extent it was up to about 1,000 kilometers wide and covered about 1.6 million square kilometers.

Was Beringia covered in ice? No. Much of it was dry steppe-tundra, which allowed large grazing animals to live there.

Where can I see Beringia today? Bering Land Bridge National Preserve and Cape Krusenstern National Monument protect parts of the former bridge in Alaska.

Sources

1. Wikipedia: Beringia
2. Encyclopaedia Britannica: History of Alaska
3. National Park Service: Alaska parks

Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 11, 2026Researched and drafted with AI assistanceReport an issue