The Thule migrate east across the Arctic to Greenland

The Thule culture grew out of the Birnirk and Punuk traditions of the Bering Strait and the north Alaskan coast, whose people hunted seals, walrus and whales from skin boats. It was defined by the Danish archaeologist Therkel Mathiassen after the Fifth Thule Expedition of 1921–1924 and named after the Thule area of north-western Greenland, where its remains had first been found, at Comer's Midden. Mathiassen thought that the migration from Alaska had taken place about a thousand years before his time, and for decades it was dated to around 1000. In 2008 T. Max Friesen and Charles Arnold published new radiocarbon dates from Nelson River and Washout, two early Thule sites on the coasts of the Beaufort Sea and Amundsen Gulf — a region through which the migrants had to pass on their way east — showing that neither site was occupied before the 13th century; this strengthened the case for a 13th-century migration that was faster and more widespread than had been believed. How fast is debated: Robert Park (2023) argues that the migration took centuries rather than decades.

Early Alaskan-style harpoon heads trace two main routes: along the Beaufort Sea coast and Amundsen Gulf into the High Arctic through Parry Channel and Smith Sound to Greenland, and south along the western shore of Hudson Bay. Why the Thule moved is debated. Robert McGhee suggested that they followed bowhead whales, whose summer range extended east as warmer centuries reduced the pack ice; others point to warfare in Alaska or to a search for iron, which the Thule obtained from meteorites — such as the Cape York meteorite in Greenland — and from the Norse. Dog sleds, umiaks and kayaks let them range over vast hunting grounds and carry heavy loads; in winter they lived in semi-subterranean houses framed with whale bones, in summer in skin tents.

The Thule replaced the Dorset, the earlier Palaeo-Eskimo people of the eastern Arctic. At Cambridge Bay radiocarbon dates suggest that Dorset people were still present around 1350, while the Thule had arrived there around 1200, yet genetic studies have found virtually no interaction between the two, and by about 1300 the Thule had largely replaced the Dorset in northern Canada and Greenland. They also came into contact with the Norse settlers of Greenland, who called the natives skrælingjar; despite centuries on the same island, no genetic admixture between the two peoples has been found. With the onset of the Little Ice Age, open-water whaling in the High Arctic ceased by the 16th century, and Thule culture gave rise to the various Inuit societies of later times.