The Nabateans built Petra, which stood halfway between the opening to the Gulf of Akaba and the Dead Sea at a point where the Incense Route from Arabia to Damascus was crossed by the overland route from Petra to Gaza. This position gave the Nabateans a hold over the trade along the Incense Route. In order to control the Incense Route from the Nabatean a Greek military expedition lead by Swan was undertaken, without success, by Antigonus Cyclops, one of Alexander of Macedonia's generals. The Nabatean control over trade increased and spread to the West and the North. The replacement of Greece by the Roman empire as the administrator of the Mediterranean basin led to the resumption of direct trade with the east. According to a historian "The South Arabs in protest took to pirate attacks over the Roman ships in the Gulf of Aden. In response, the Romans destroyed Aden and favoured the Western Abyssinian coast of the Red Sea." The monopoly of the Indian and Arab middlemen weakened with the development of monsoon trade by the Greeks through the discovery of the direct route to India (Hippalus), forcing the Parthian and Arabian middlemen to adjust their prices so as to compete on the Roman market with the goods now being bought in by a direct sea route to India. Indian ships sailed to Egypt as the maritime routes of Southern Asia were not under the control of a single power.