An early (1820-1840) Cheyenne style - the rawhide covered and carved body tucks under the belt and the pound beaded flap goes over the top to keep it from slipping down - the two thongs can then be tied to the belt or as an alternative can be laced through the flap to form a belt loop. The beadwork and carving are based on an earlier (1810 or so) original that was quilled but I used the beads in the same basic colors instead.
here's the original sheath that I used for inspiration - some sources note this is may be an Eastern Sioux product, but the quillwork pattern is very typical of the Cheyenne, even their later beadwork.
