These figures have an extraordinary quiet intensity.
This craft, perfected by the Yoruba people, is continued from the 15th century in Benin - still today a great centre of metal casting.
Cast metal is the only other material to withstand the continent's termites (fatal to the carved wood of most African sculpture).
But the superb metal sculptures of Nigeria, beginning in about the 12th century, are of a much later period than the first terracottas.
Powerful terracotta figures in traditional style continue to be made in Africa in the 19th and 20th century, contemporary with the superb carved wooden figures which survive from those two centuries.
Unlike European painting or sculpture, style does not greatly change over the years in African tribal art.
The Benin heads, delightful but less powerful in their impact than those of Ife, are commonly known as Benin bronzes.
In fact they are made of brass, melted down from vessels and ornaments arriving on the trade routes (in 1505-7 alone, the Portuguese agent delivers 12,750 brass bracelets to Benin).
The other is the sculpture of Africa, distorting human features and limbs in a dramatically expressive manner.A figure may represent an ancestor, destined to stand in a shrine.A mask may be intended for use by a shaman just once a year in a special dance.West Africa, and in particular modern Nigeria, provides the longest and richest sequence of terracotta figures.They date back two and a half millennia to the extraordinary Nok sculptures.So it is a safe assumption that the astonishing imaginative range of African carving familiar to us today was just as evident many centuries ago, though the objects themselves have now crumbled to dust.