This mask was possibly used in combined masquerades and puppet plays/entertainments put on by young men's age-grade associations (kamalen-ton) especially in the region around Segou. In addition to human marionettes carved of wood which embody various characters, animal figures and masks (sogo-kun) also appear. They are expressive and are strongly colored with oil paints.

Sogo-bò is a puppet masquerade drama that did originate with Bozo fishermen. By the late nineteenth century, however, Bamana within Ségou began to adopt the masquerade theater and throughout the last century it flourished in these farming communities. It now has a regional identity and is performed in many Bamana communities within south central Mali. It is defined by the community as nyènajè (entertainment) and tulon (play).

This comes from Andrew Turley, a young collector of African masks. Check out his excellent site-- http://www.suagacollection.com/