1727 - 1780s French expeditions

        The expansion of French commercial interests in the Great Lakes region of Canada began to grow rapidly once Sieur de La Verendrye was appointed commandant in 1727.  Until then, the French had ventured no farther west than Lake Superior, but in the next ten years the intrepid Frenchman and his sons would establish a string of new trading posts that reached the Assiniboine River, in Manitoba. 

        From there, La Verendrye launched his overland expedition to find the Mandan Villages after hearing rumors from various traders of a great civilization that lived underground, and were said to have fields of corn, melons, pumpkins, squash and beans.