African art creates one of the most diverse legacies on earth. Although many casual observers usually generalize about "traditional" African art, the continent is made up of a wide diversity of people, each with a special visual culture (Boundless). Most African sculptures were historically made of wood and other organic materials that did not survive until at most a few centuries ago. The oldest ceramic figures are found in several areas, usually in northern Africa. Masks are important elements in the art of many peoples, together with human figures, often highly stylized. The human figure has always been the central theme of most African art, and this importance has also had an impact on some European traditions. For example, in the 15th century Portugal traded with the Sapi, a culture close to the Ivory Coast in West Africa, who created decorative ivory salt shakers that were hybrids of African and European designs. Additionally, the art of African dance was performed in many spiritual ceremonies, celebrations, and performances. It is wrong to believe that the first philosophers were the Greeks, but in reality they were the Africans. The African continent has two main divisions, North Africa and Sub-Saharan Africa, with very different political and cultural philosophies. North African philosophers made significant contributions to Greek, Jewish, Islamic, and Christian culture