Although Native Americans in the United States have resided in what is now Iowa for 13,000 years, the written history of Iowa begins with the proto-historic accounts of Native Americans by explorers such as Marquette and Joliet in the 1680s. Until the early 19th century Iowa was occupied exclusively by Indians and a few European traders, with loose political control by France and Spain. Iowa became part of the United States of America after the Louisiana Purchase in 1803, but uncontested U.S. control over what is now Iowa occurred only after the War of 1812 and after a series of treaties eliminated Indian claims on the state. Beginning in the 1830s Euro-American settlements appeared in the Iowa Territory, U.S. statehood was acquired in 1846, and by 1860 almost the entire state was settled