Beringia is a massive, now-submerged prehistoric landmass that once connected Asia and North America. This vast region emerged during glacial periods when global sea levels dropped dramatically due to water locked in continental ice sheets. While often called the land bridge, Beringia was a geographical area encompassing the exposed seafloor of the Bering and Chukchi Seas, along with portions of modern-day Siberia and Alaska. Its existence provided an intercontinental link, enabling the movement of flora, fauna, and eventually human populations between the Old and New Worlds.
The Geography and Timeline of the Land Bridge
The formation of the Bering Land Bridge was a direct consequence of eustatic sea level change during the Pleistocene Epoch. As the Laurentide and Cordilleran ice sheets expanded, they sequestered enormous amounts of water, causing the global sea level to fall by as much as 400 feet (120 meters). Because the continental shelf beneath the Bering Strait is shallow, this drop exposed a massive tract of dry land.
This exposed landmass was not a narrow strip but a huge, unglaciated territory that stretched up to 1,000 miles (1,600 kilometers) from north to south at its widest point. The area extended from the Lena River in Russia eastward to the Mackenzie River in Canada. The most recent and significant period of exposure began when the land bridge emerged around 35,700 years ago.
The land connection remained largely intact until about 11,000 years ago, spanning the Last Glacial Maximum (LGM) between 26,000 and 19,000 years ago. The subsequent global warming and melting of the ice sheets gradually raised the sea level. This process ultimately submerged the central portion of Beringia, permanently severing the connection between the continents.
The Beringian Steppe Ecosystem
Despite its high northern latitude, the heart of Beringia remained largely free of the major ice sheets covering North America and Eurasia. The intensely cold climate was also extremely dry, preventing the necessary snowfall accumulation for massive glacier formation in the lowlands. The resulting environment was a unique, treeless landscape known as the Beringian Steppe-Tundra, or the Mammoth Steppe.
This ecosystem was a “no-analogue” biome, meaning it has no exact modern counterpart. It was characterized by cold, arid conditions but maintained high biological productivity. Unlike the wet, modern Arctic tundra, the Mammoth Steppe was a dry grassland dominated by palatable, nutritious grasses, sedges, and herbs, such as sage (Artemisia).
The dry climate and wind likely created conditions that kept snow cover thin or scoured away, allowing large herbivores to graze throughout the year. This abundance of forage supported a diverse community of megafauna. Herds of woolly mammoths, steppe bison, and extinct Yukon horses (Equus lambei) moved across the vast plains. These grazers were preyed upon by specialized carnivores like the scimitar cat and the giant short-faced bear, forming a complex food web.
The Role in Human Movement to the Americas
The unglaciated, productive environment of Beringia served as a temporary homeland and a gateway for the Paleo-Indians, the first human populations to enter the Americas. Anthropological and genetic evidence suggests that a population of proto-Americans lived in Beringia, isolated from their Asian ancestors, for a period known as the “Beringian Standstill.” They remained isolated for thousands of years before expanding southward into the interior of the Americas.
The timing and route of this final expansion remain a major topic of debate, with two primary theories detailing the potential paths south. The Ice-Free Corridor (IFC) theory suggests that humans moved inland through a narrow, temporary passage between the Cordilleran and Laurentide ice sheets. Geological data indicates this route was viable around 14,800 years ago, but the earliest definitive archaeological sites south of the ice sheets often predate its full opening.
The alternative, the Coastal Migration Theory, proposes that early peoples bypassed the ice sheets entirely by moving along the Pacific coastline, possibly utilizing watercraft. Sites like Monte Verde in southern Chile, dated to at least 14,500 years ago, support a rapid, early dispersal down the Pacific coast, suggesting accessibility before the inland corridor opened. Early archaeological sites in eastern Beringia, such as Bluefish Caves in the Yukon, provide evidence of human presence dating to around 14,000 years ago, marking the beginning of the journey into North America.
Modern Remnants: The Bering Strait
The vast land bridge ultimately disappeared as the global climate warmed and glaciers melted, a process that began around 15,000 years ago. The resulting influx of meltwater caused sea levels to rise steadily, gradually inundating the low-lying central plains of Beringia. This submergence created the Bering Strait, the narrow waterway that today separates Asia and North America and connects the Arctic Ocean to the Bering Sea.
Remnants of this prehistoric landscape are found on the coastlines of Siberia and Alaska, where the former land bridge meets the present-day shore. The most accessible part of this ancient region is preserved in the Bering Land Bridge National Preserve on the Seward Peninsula in Alaska. This protected area safeguards the unglaciated tundra that once formed the eastern edge of the landmass, offering a tangible connection to the world of the Mammoth Steppe.