Petra is about 262 km south of Amman, about 133 km to the north of Aqaba. The Nabateans carved this city into the soft rose Nubian sandstone more than two thousand years ago. Petra was re-discovered in 1812 by the Swiss explorer J. Burchhardt. The Nabateans were semi-nomadic coming from the northern Arabian Peninsula during the sixth and fifth centuries BC. Their organization was remarkable. This empire was established on trade flow and not on land possession. They carried on their caravans products of great value. Their use of camels and their knowledge of irrigation are the origin of their success. In 106 AD, the kingdom was annexed and integrated into the Roman Empire by Emperor Trajan. Petra declined progressively when trade between the Orient and the Occident was oriented towards the Euphrates to the advantage of Palmyra, in Syria, and after several earthquakes.