The inclusion of metal probably influenced the original tentative identification of this as a Kota headrest because of the prevalence of metal on the well-known Kota reliquary figures. based on the form of these two headrests, however, it might be better to ascribe them to the area of the middle Zaire, or on either side of the lower Kasai River. Maes offers the only apparent source providing clues regarding the origin of these headrests.
Source: Dewey, William J. (1993): “Sleeping Beauties: The Jerome L. Joss Collection of African Headrests at UCLA”‚ Los Angeles, UCLA Fowler Museum of Cultural History. page 52