In 272 AD a queen was racing across the Syrian desert on a famously fast camel, trying to reach the Euphrates before the Roman emperor's cavalry reached her. Zenobia of Palmyra had spent five years turning a caravan city into an empire. The opening was Rome's own collapse: the crisis of the third century brought hyperinflation, plague, invasions on two frontiers, and 26 claimants to the throne in fifty years. Palmyra sat on the Silk Road and the incense routes, cosmopolitan and enormously rich, and when Rome's authority buckled it had both the money and the position to step forward. Her husband Odaenathus had already saved the Roman East after the emperor Valerian was captured alive by the Persians, and Rome, desperate, handed him extraordinary authority. When he and his eldest son were assassinated in 267, Zenobia moved instantly to secure power ...