 Archaeological evidence of Native American settlements dates back as far as 3000 BC ; the Jeffers Petroglyphs site in southwest Minnesota contains carvings thought to date to the Late Archaic Period ( 3000 BC to 1000 BC ) . Around 700 BC , burial mounds were first created , and the practice continued until the arrival of Europeans , when 10 @,@ 000 such mounds dotted the state . 
