Ancient people lived in Minnesota as early as 12,000 years ago, moving seasonally between camps while hunting and gathering. They often chose camps near major waterways such as the Minnesota and Mississippi rivers to take advantage of fresh water fish, game animals, wild plants, and transportation resources. Archaeologists have excavated some Native American village and camp sites in the area and found tools, arrow points, pieces of pottery, animal bones, and plant remains, which provide a better understanding of how Native Americans lived. One group in this region was known for impressive burial mounds. Some of these mounds survive, while others have been disturbed or destroyed by plowing, looting, road building, and other development activities. Today, existing mounds are protected from all disturbance by state law.