Antique native American Knife/Sheath

Very old native American Knife/Sheath.Sheath seems to be made of untanned hide with fringes(stiff)Front is painted with what appears to be a turtle and below that..a bear paw.Sheath is sewed using only sinew.(About 10 inches long)Knife fits sheath perfectly. Knife has a hide covered handle with a well used blade with beautiful patina. Blade was covered in rust when I acquired it but metal underneath was still very good and wd40 removed the rust but didnt affect the patina. Rawhide handle cover is also sewed with sinew. Does anybody have any thoughts on the tribal affiliation or time period?