Pierre Gaultier de la Verendrye was the first-known white man to enter what is now North Dakota. He was a 53-year-old fur trader and explorer who set out in the fall of 1738 from Fort La Reine west of present Winnipeg to find “the Western Sea” and the “Mantanne” tribe who lived along “the River of the West” – the tribe that would become known as the Mandan.