From Wikipedia
The area around Petra has been inhabited from as early as 7000 BC, and was settled by the Nabataeans, a nomadic Arab people, in the 4th century BC. Petra would later become the capital city of the Nabataean Kingdom in the second century BC. The Nabataeans invested in Petra's proximity to the incense trade routes by establishing it as a major regional trading hub, which gained them considerable revenue. Unlike their enemies, the Nabataeans were accustomed to living in the barren deserts and thus were able to defend their kingdom. They were particularly skillful in agriculture, stone carving, and rainwater harvesting.
Petra flourished in the 1st century AD, when its Al-Khazneh structure, possibly the mausoleum of Nabataean king Aretas IV, was constructed, and its population peaked at an estimated 20,000 inhabitants.[ Nabataea fell to the Romans in 106 AD, who annexed and renamed it Arabia Petraea. Petra's importance declined as sea trade routes emerged, and after an earthquake in 363 destroyed many structures. In the Byzantine era, several Christian churches were built, but the city continued to decline and, by the early Islamic era, it was abandoned except for a handful of nomads. It remained unknown to the western world until 1812, when Swiss traveller Johann Ludwig Burckhardt rediscovered it.
UNESCO has described Petra as "one of the most precious cultural properties of man's cultural heritage". Petra is a symbol of Jordan, as well as Jordan's most-visited tourist attraction. Visitor numbers reach close to a million tourists every year.
