About the sixth century B.C. schools of medicine existed on the island of Cos, Greece, where philosophers theorized on the nature of man and the universe. The Pythagoreans (followers of Greek philosopher and mathematician Pythagoras, c. 580–500 B.C.) began the first schools of higher education in southern Italy, where philosophy and mathematics were taught in Greek. The great philosophers Socrates, Plato, and Aristotle carried on the Pythagorean tradition, as did Epicurus and Zeno in the fourth century B.C. Universities have a long history in the Arab world; for example, the Al-Azhar University in Cairo was founded in about A.D. 970 and is one of the oldest universities in the world.