Head of a Queen Mother (Iyoba)...

Head of a Queen Mother (Iyoba) 
1750–1800 - Nigeria, Court of Benin 
Courtesy: The MET Museum of Art

In the Benin kingdom, the iyoba, or mother of the oba (king), occupies an important and historically significant place within Benin's political hierarchy.

The title was first conferred upon Idia, the mother of king Esigie, who used her political skill and supernatural abilities to save her son's kingdom from dissolution in the late fifteenth century.

Ever since that time, queen mothers have been considered powerful protectors of their sons and, by extension, the kingdom itself.

Because of the enormous esteem in which they are held, iyobas enjoy privileges second only to the oba himself, such as a separate palace, a retinue of female attendants, and the right to commission cast brass sculptures for religious or personal use...   http://tribart.blogspot.fr/2017_02_01_archive.html#1755759189924177816