Shown here is a manuscript map depicting the “course of the rivers and streams flowing westward from the north of Lake Superior.” The anonymous author of the map composed it “following a chart made by the Indian Ochagac and others.” Ochagac’s description of an “undrinkable body of water” with “ebb and flow” led the anonymous French mapmaker to draw conclusions about a great “Western River” that discharged itself into the “South Sea” (Pacific Ocean). The map shows different Native American nations, including the Sioux and the Assiniboine. The scale is given in lieues (leagues), an old French measurement that varied by degrees and time (very approximately, one lieu = three kilometers). In December 1730 the French explorer and fur trader Pierre Gaultier de Varennes, sieur de La Vérendrye (1685–1749), presented to the governor of Canada, Charles de la Boische, Marquis de Beauharnois, a plan to find the Western Sea, based upon information provided by Ochagac (also seen as Auchagah, a Cree from around Fort Kaministiquia). In 1731, La Vérendrye obtained a concession for the fur trade monopoly in the lands of the Sioux to finance his expeditions. From 1731 to 1744 La Vérendrye and three of his sons, Jean-Baptiste, Pierre, and François, searched for the Western Sea by way of the Great Lakes. Although he did not find the Western Sea, La Vérendrye explored the region from Fort Kaministiquia (north of Lake Superior) to Lakes Winnipeg and Manitoba and the White River (Saskatchewan) and created a series of trading posts, including Fort Maurepas (on the Red River) in 1734 and Fort La Reine (at present-day Portage La Prairie) in 1738.