Watch Petra, the Capital of the Desert for Free: How to Stream the Movie Online at 123Movies. . At the dawn of the Christian era, Petra, capital of the rich kingdom of the Nabataeans, bordering the deserts of Arabia, Syria and the Negev, was absorbed by the Roman Empire and, after being sacked by the Bedouins, disappeared from the memory of mankind; but its secrets are gradually being revealed thanks to an enormous excavation work.