The Yoruba peoples of Nigeria have what is probably the longest extant artistic tradition in Africa. The nation state is comprised of numerous subsections that were joined historically by the rise and collapse of the Ife (12th to 15th centuries) and Benin (13th to 19th centuries) polities. Each of the sub-kingdoms – including Oyo, Ijebu and smaller units towards the west – had their heyday, and are loosely united through language and culture, although they still retain a measure of independence in terms of their artistic traditions. It is extremely hard to summarise the nature of Yoruba society given the large area they cover and the inevitable variability of their customs.

The Yoruba – being a large, complex society – is sedentary, agriculturist and hierarchical. They are ruled by hereditary kings known as Obas, and their access to the supernatural world is supervised by a very complex arrangement of priests (i.e. Olowa) and spiritual intermediaries. Their cosmology is arranged in terms of the tangible realm of the living (aye) and the invisible realm of the spirits and the hereafter (orun). Their relationship is sometimes described as being that of a gourd with tightly-interlocking upper and lower halves, or as a divination board with a raised rim and a depressed centre. The creator of the world is Olodumare (or Odumare, Olorun, Eleda or Eleemi, depending on the area), who is the source of all ase – life force. Orun is populated by all manner of spirits (iwin, ajogun, egbe and oro), gods (orisa) and ancestors (ara orun), all of whom influence the living. They can all be reached, appealed to or appeased through human intermediaries such as the babalawo (diviner). Most Yoruban artistic heritage is designed to thwart evil spirits, and to placate or honour those that bring good fortune to the populace.

Yoruba populations have the world’s highest prevalence of twinning (45/1000 live births – compared to 8/1000 in the US), and this fact has been woven into their mythology, culture and art. In Yoruba culture, twins are promulgated by Shango, who is also the god of Thunder. Twins are thus regarded as auspicious – fertility is, after all, a major factor in determining the viability of any population. However, the mortality rate of twins is very high (approximately 50%), and magico-religious measures have been taken to avert this misfortune. According to Yoruba convention, every person has a spirit or soul, which is shared between a pair of twins. If one should die, the babalawo (diviner) will carve a wooden figure of the same sex as the deceased child, which the parents must take care of as if it were alive. This figure is known as an ere ibeji. The protector of twins – a spirit (orisha) named Ibeji – will then safeguard the remaining child until adulthood. Until this point, the mother must wash, dress, feed and anoint the wooden figure. The appearance of the figures depends entirely upon the skill of the carver, as only the sex of the individual is specifically determined. The specific social history of the area, and its contacts with other areas or cultures, does determine the final appearance of the figures. For example, the hair of some individuals is rubbed with indigo dye, and the bodies with red camwood powder, while tribe-specific scarifications enable one to determine the origin of the figure within the Yoruba polity. Equally, most ibeji are naked, but socially elevated families often wish to manifest their wealth through dressing the figure in ornate clothing or jewellery.