The European exploration of the north in the 19th century built on the legacy of the preceding 300 years. By 1851 several missing pieces of the Arctic archipelago and coastline had been charted, but in this hostile, uncompromising territory the northern hinterland, away from the shores and rivers, remained unknown. Adversity accompanied every expedition, and the north, with its cold, ice, lack of food, rough water, mountains, muskeg, and mosquitoes, continued to take its toll. The major players remained the British Admiralty and the Hudson's Bay Company (HBC). The former continued England's centuries-long search for a Northwest Passage, sending expeditions westward across land and along sea lanes to define much of the Arctic shore. After the loss of John Franklin and his crew in the heart of the archipelago in 1845, British explorers narrowed their focus to sea quests for their lost comrades. The HBC, in turn, continued its search for geographical information, as exemplified by the peregrinations of Peter Dease and Thomas Simpson, but also lent support to Admiralty expeditions. Other HBC activity was concentrated in the west, on the Mackenzie River and along routes to the Pacific, with the Liard and Peel rivers through the Cordillera emerging as the chosen routes of access. The long-attempted integration of the Pacific watershed with the Mackenzie District occurred when Robert Campbell journeyed downstream from the Yukon-Felly junction to Fort Yukon at the confluence of the Yukon and Porcupine rivers in 1851. For some years the HBC lost interest in northern Quebec and Labrador, but in 1828 it renewed exploration and began to build posts from the newly established Fort Chimo at Ungava, hoping to bring the area into its marketing system. Erland Erlandson and John McLean helped delineate the major waterways from Fort Chimo southeast to Hamilton Inlet.
In 1833 Captain George Back of the Royal Navy and surgeon-naturalist Richard King sought a land route across the Arctic Barren Lands in an attempt to determine the fate of the missing 1829 John Ross expedition and to pursue the survey of the Arctic coast in the quest for a Northwest Passage. Back's exploration of 1833-4 not only produced new geographical knowledge that made possible improvements in Arrowsmith's revised map of 1835, but also contributed scientifically valuable observations of wildlife, magnetic effects, and the aurora borealis.