Petra was an ancient city south of the Dead Sea in what is now Jordan.  It was an important trading centre from the late 400's B.C. to the early A.D. 200's.  The city stood on the overland trade route that linked Arabia and the Mediterranean Sea.  The Nabataeans, a group of Arabian people, came to power in Petra in the 400's B.C. In A.D. 106, Roman forces conquered Petra and made it part of the Roman Empire.  Petra prospered from A.D. 106 to the early 200's.  The people built temples on the plain there, and they cut deeply into the cliffs to make houses.  Petra had often been called the rose-red city because of its red stone buildings and the red cliffs surrounding it. 

About A.D. 235, Petra suddenly stopped making coins, and Palmyra, a city in Syria, took over most of Petra's trade.  Petra then became chiefly a religious centre.  It became a Christian city by the A.D. 300's.  Muslims captured the city in the 600's.  The Franks, a Germanic tribe, occupied it during the Crusades, and held it until 1189.  Soon after, the city was abandoned, and it fell into ruin.