The Nabataean kingdom was one of the wealthiest of the Client States which were a prominent feature on the Roman frontiers, especially in the east. Its capital at Petra is famous for its spectacular civic buildings and tombs. It was annexed by Trajan who created the new province of Arabia.
The Nabataeans were early nomadic Arabs who traveled across the deserts of Arabia for trade. Although not as well known as other ancient civilizations, the Nabataeans were trade savvy and developed ingenious hydraulic engineering systems, some remains of which can be seen in Petra today. These two elements combined enabled the Nabataeans to control important trade routes. They not only operated from Petra – the region that in the bible is called Edom – but also throughout Moab and other regions from southern Syria to the western Sinai. By the fourth century B.C. the Nabataeans controlled the spice and incense trade from Arabia to Mesopotamia.
Their efficient water storage techniques, which included hidden underground cisterns strategically located along their trade routes, allowed the Nabataeans to cross vast expanses of desert, brining frankincense and spices from Arabia and from the East to the Mediterranean. Thus Petra flourished in the first centuries B.C. and A.D., despite the extremely arid environment, by the engineering of a sophisticated hydrological system. The system brought water in channels and clay pipes from springs near Petra, notably from Ain Musa which is located in present-day Wadi Musa. The system also harvested the meager yearly rainfall and mitigated the effects of the rare downpours that would otherwise have produced destructive flash floods.
In continually seeking to improve their position in a trading network that included Greece, Persia, Rome, India, and Arabia and that stretched ultimately to China, the Nabataeans provided a conduit for goods and ideas among these groups. The architecture of Petra that survives today testifies to the exchange of cultural traits that occurred on a global scale even in ancient times. Tombs and buildings display Assyrian, Egyptian, Hellenistic, Babylonian, and Roman characteristics incorporated into a Nabataean style that, especially in its earlier expressions, owes much to the architectural tradition of the East.