The Old World consists of Europe, Asia, and Africa, regarded collectively as the part of the world known before the discovery of the Americas. It is used in the context of, and contrast with, the New World. The Old World comprises Africa, Asia, and Europe (collectively known as Afro-Eurasia), plus surrounding islands (or at least those parts known to classical geography before the 15th century). The concept of the three continents in the Old World goes back to classical antiquity.