Straddling the northern end of the caravan route from South Arabia to the Mediterranean, the Nabataean kingdom emerged as a great merchant-trader realm during the first centuries B.C. and A.D. Previously nomads in northern Arabia, the Nabataeans had already settled in southern Jordan by 312 B.C., when they attracted the interest of Antigonus I Monophthalmos, a former general of Alexander the Great who unsuccessfully attempted to conquer their territory. By that time, the city of Petra (ancient Raqmu) was the center of the Nabataean kingdom, strategically situated at the crossroads of several caravan routes that linked the lands of China, India, and South Arabia with the Mediterranean world. The fame of the Nabataean kingdom spread as far as Han-dynasty China, where Petra was known as Li-kan. The city of Petra is as famous now as it was in antiquity for its remarkable rock-cut tombs and temples, which combine elements derived from the architecture of Egypt, Mesopotamia, and the Hellenized West.
During the reign of King Aretas III (r. 86–62 B.C.), the Nabataean kingdom extended its territory northward and briefly occupied Damascus. The expansion was halted by the arrival of Roman legions under Pompey in 64 B.C. At various times the kingdom included the lands of modern Jordan, Syria, northern Arabia, and the Sinai and Negev deserts. At its height under King Aretas IV (r. 9 B.C.–40 A.D.), Petra was a cosmopolitan trading center with a population of at least 25,000. The kingdom remained independent until it was incorporated into the Roman province of Arabia under the emperor Trajan in 106 A.D.