In reality, while Alexander did travel a great deal, he did not travel further west than ancient Libya and did not travel further east than the fringes of India. According to historians, Alexander invaded India following his desire to reach the "ends of the world and the Great Outer Sea." However, when he reached the Hyphasis River in the Punjab in 326 BC, his army nearly mutinied and refused to march further east, exhausted by years of campaigning. Alexander's desire to reach "the ends of the Earth" was instilled by his tutor Aristotle: