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First contact with Europeans

The Dakota are first recorded to have resided at the source of the Mississippi River and the Great Lakes during the seventeenth century. They were dispersed west in 1659 due to warfare with the Iroquois. During the 1600s, the Lakota began their expansion westward into the Plains, taking with them the bulk of people of the Očhéthi Šakówiŋ. By 1700 the Dakota were living in Wisconsin and Minnesota. As the Sioux nation began expanding with access to horses, the Dakota were put in a weakened position to defend the eastern border: new diseases (smallpox and malaria) and increased intertribal warfare (between the migration of tribes fleeing the Iroquois into their territory of present-day Wisconsin) put a strain on their ability to maintain their territory. As a result, their population in the Mississippi valley is believed to have declined by one-third between 1680 and 1805.