Humans have inhabited the land now known as Missouri for at least 12,000 years. The Mississippian culture built cities and mounds, before declining in the 14th century. When European explorers arrived in the 17th century, they encountered the Osage and Missouria nations. The French established Louisiana, a part of New France, founding Ste. Genevieve in 1735 and St. Louis in 1764. After a brief period of Spanish rule, the United States acquired the Louisiana Purchase in 1803. Americans from the Upland South, including enslaved African Americans, rushed into the new Missouri Territory. Missouri was admitted as a slave state as part of the Missouri Compromise. Many from Virginia, Kentucky and Tennessee settled in the Boonslick area of Mid-Missouri. Soon after, heavy German immigration formed the Missouri Rhineland.