The Inuvialuit are the Inuit of the Western Canadian Arctic. Inuvialuit trace their origins to the Thule culture, which developed in Alaska more than one thousand years ago and soon after spread into what is now the Canadian Arctic. At the time Europeans arrived in Inuvialuit territory in the early 19th century, Inuvialuit were living in named groups with well-defined territories along the lower reaches of the Mackenzie River and along the shorelines of the Beaufort Sea. The rich resources of this territory allowed them to live in large communities of up to several hundred people, the largest communities in the Canadian Arctic.