Alexander's unrelenting desire to press on resulted in a perilous seven-year journey through the unknown eastern borderlands of the Persian empire that would test the great conqueror's physical and mental limits. He faced challenges from the natural world, moving through deadly monsoons and extreme temperatures; from a rotating cast of well-matched adversaries, who conspired against him at every turn; and even from his own men, who questioned his motives and distrusted the very beliefs on which Alexander built his empire. This incredible sweep of time, culminating with his death in 323 BC at the age of 32, would come to determine Alexander's legacy and shape the empire he left behind.