Who explored much of Canada and the Great Plains, mapping the rivers of the West.

Henry Kelsey

Explanation:

Henry Kelsey was a British explorer who led an expedition in 1690 into the great plains of Canada and mapped out the rivers in uncharted west. for the expedition he used local knowledge and learned many Indian languages to effectively communicate with the natives.

He would later play a big role in the establishment of the Hudson's Bay Company that monopolized the gains from the newly charted Canadian territory.