Alexander the Great also known as Alexander III, was an ancient Greek king of Macedon (336–323 BC). He was one of the most successful military commanders in history, and was undefeated in battle. By the time of his death, he had conquered most of the world known to the ancient Greeks. Following the unification of the multiple city-states of ancient Greece under the rule of his father, Philip II of Macedon, Alexander conquered the Persian Empire, including Anatolia, Syria, Phoenicia, Judea, Gaza, Egypt, Bactria and Mesopotamia and extended the boundaries of his own empire as far as the borders of Punjab. Before his death, Alexander had already made plans to also turn west and conquer Europe. He also wanted to continue his march eastwards in order to find the end of the world, since his boyhood tutor Aristotle had told him tales about where the land ends and the Great Outer Sea begins.