Petra was first established as a city by the Nabataean Arabs in the 4th century BCE, and owed its birth and prosperity to the fact that it was the only place with clear and abundant water between the Hijaz trading centres of Mecca and Medina, and Palestine. Hewn directly into the Nubian sandstone ridges of the south Jordanian desert, it seems probable that - given its excellent defensive position and good water supplies - Petra has been continually occupied from as early as Paleolithic times. It is thought to be mentioned in the Bible as Sela, a mountain fortress captured by Amaziah, King of Judah, in the 9th century BC, when the defenders were hurled to their deaths from the summit, and as many as 10,000 people died. The city's Latin name, Petra - literally, 'Rock' - probably replaced the biblical name Sela at the time of the Roman conquest some 1,900 years ago. Today, in Arabic, the ancient site is still called Batraa, though the valley in which it is situated is known as Wadi Musa -