After Alexander defeated the last of the Achaemenid Empire’s forces in 328 BC, he began a new campaign to Ariana in 327 BC. He wanted to conquer the entire known world, which in Alexander’s day, ended on the eastern end of India. Greeks of Alexander’s day knew nothing of China, or any other lands east of Bactria. The Siege of the Sogdian Rock, a fortress located north of Bactria in Sogdiana, occurred in 327 BC. Oxyartes of Bactria had sent his wife and daughters, one of whom was Roxana, to take refuge in the fortress, as it was thought to be impregnable, and was provisioned for a long siege. When Alexander asked the defenders to surrender, they refused, telling him that he would need “men with wings” to capture it. Alexander asked for volunteers, whom he would reward if they could climb the cliffs under the fortress. There were some 300 men who from previous sieges had gained experience in rock-climbing. Using tent-pegs and strong flaxen lines, they climbed the cliff face at night, losing about 30 of their number during the ascent. In accordance with Alexander’s orders, they signaled their success to the troops below by waving bits of linen, and Alexander sent a herald to shout the news to the enemy’s advanced posts that they might now surrender without further delay. The defenders were so surprised and demoralized by this that they surrendered. Alexander fell in love with Roxana, whom ancient historians call the “most beautiful woman in the world” on sight and eventually married her. The story of the siege is told by the Roman historian Arrian of Nicomedia, in Anabasis.