In the time of the Nabataeans (about 2000 years ago), Petra was an important hub on the trade routes linking China in the east with Rome in the west. In the middle of the desert, Petra had water in abundance and offered protection from raiders. The Nabataeans had their hospitality paid for in the form of tolls on all goods and thereby achieved considerable wealth.
When Christianity spread throughout the Byzantine Empire, the once magnificent city vanished from the consciousness of the Western world, until the Swiss traveller Johann Ludwig Burckhardt, disguised as an Arab, rediscovered the city on 22 August 1812.
(Source: Weltatlas.Info)