Although Africa north of the Sahara and the coasts of the Red Sea and East Africa were well known to the ancient Mediterranean world, Africa south of the desert was not. By the fifteenth century, European perceptions of the land and people of sub-Saharan Africa were shrouded in myth, distorted by legends of ferocious peoples with bizarre physical features. Africans were collectively called Ethiopians, a pejorative term having nothing to do with the Ethiopians of northeast Africa. From the middle of the fifteenth century, the dramatic discovery of Africa by Europe was made possible by the Portuguese voyages of exploration around the African coast. These voyages were carefully planned, but their execution down the African coast was painfully slow. The long, inhospitable western African coast had few natural harbors and dangerous shores, shoals, and ocean currents that required methodical exploration to understand and chart accurate nautical maps; this could only be achieved by substantial innovations in shipbuilding, seamanship, and navigation, which required more than six decades to devise before the Portuguese captains could round the Cape of Good Hope.