 The oldest known human remains in Minnesota , dating back about 9000 years ago , were discovered near Browns Valley in 1933 . " Browns Valley Man " was found with tools of the Clovis and Folsom types . Some of the earliest evidence of a sustained presence in the area comes from a site known as Bradbury Brook near Mille Lacs Lake which was used around 7500 BC . Subsequently , extensive trading networks developed in the region . The body of an early resident known as " Minnesota Woman " was discovered in 1931 in Otter Tail County . Radiocarbon dating places the age of the bones approximately 8 @,@ 000 years ago , approximately <unk> ± 70 BP or near the end of the Eastern Archaic period . She had a conch shell from a snail species known as Busycon <unk> , which had previously only been known to exist in Florida . 
