The United States acquired this territory east of the Mississippi River and north of the Ohio River after it gained independence from the United Kingdom. As white settlers moved into the region from the United States' eastern areas, beginning in the early 19th century, the Kickapoo were under pressure. They negotiated with the United States over their territory in several treaties, including the Treaty of Vincennes, the Treaty of Grouseland, and the Treaty of Fort Wayne. They sold most of their lands to the United States and moved north to settle among the Wea.