Aornos () was the Ancient Greek name for the site of Alexander the Great's last siege, which took place on April 326 BC, at a mountain site located in modern Pakistan. Aornos offered the last threat to Alexander's supply line, which stretched, dangerously vulnerable, over the Hindu Kush back to Balkh, though Arrian (although disbelieving himself of this story) credits Alexander's desire to outdo his kinsman Heracles, who allegedly had proved unable to take a fort that the Macedonians called Ἄορνος Aornos (according to Arrian and Diodorus; Aornis according to Curtius; elsewhere Aornus): meaning birdless in Greek. According to one theory, the name is a corruption of an Indo-Iranian word, such as *awarana fortified place. According to Arrian, the rock had a flat summit well-supplied with natural springs and wide enough to grow crops: it could not be starved into submission. Neighboring tribesmen who surrendered to Alexander offered to lead him to the best point of access.