A now-independent and warlike Sogdiana formed a border region insulating the Achaemenid Persians from the nomadic Scythians to the north and east. It was led at first by Bessus, the Achaemenid satrap of Bactria. After assassinating Darius III in his flight from the Macedonian Greek army, he became claimant to the Achaemenid throne. The Sogdian Rock or Rock of Ariamazes, a fortress in Sogdiana, was captured in 327 BC by the forces of Alexander the Great, the "basileus" of Macedonian Greece and conqueror of the Persian Achaemenid Empire. Oxyartes, a Sogdian nobleman of Bactria, had hoped to keep his daughter Roxana safe at the fortress of the Sogdian Rock, yet after its fall Roxana was soon wed to Alexander as one of his several wives. Roxana, a Sogdian whose name "Roshanak" means "little star", was the mother of Alexander IV of Macedon, who inherited his late father's throne in 323 BC (although the empire was soon divided in the Wars of the Diadochi).