along the Silk Road, was surprised when Alexander had advanced through Gedrosia and Arachosia and crossed the Hindu Kush mountains in 329 BC to invade Bactria. Bessus fled north to Sogdia where he too was betrayed and was handed over to Alexander by his courtiers, Spitamenes and Datames. In July 329 BC, as Alexander founded the city of Alexandria Eschate on the northern border of Sogdia, Spitamenes led a revolt and besieged the Sogdian capital of Maracanda. A Scythian incursion into Sogdia prevented Alexander from responding personally, however, once he had defeated the Scythians in the Battle of Jaxartes, he marched south to relieve Maracanda causing Spitamenes to move south and attack Balkh in the winter of 329 BC. In the spring of 328 BC, Alexander sent his general Craterus to fortify Margiana, where he established a garrison in Merv and re-founded the city as Alexandria in Margiana. Alexander's general Coenus defeated Spitamenes in the Battle of Gabai in December 328 BC, and subsequently in the following year Sogdia was merged with Bactria to form a single satrapy under the rule of Philip. Hellenistic Period Upon Alexander's death in 323 BC, the empire was partitioned between his generals at the Partition of Babylon and according to some historians, Philip remained as satrap of Bactria, however, it has also been suggested that he was in fact only satrap of Sogdia. Disagreements between the generals led to another meeting and in the Partition of Triparadisus in 321 BC, Philip was replaced as satrap of Bactria and Sogdia by Stasanor. During the Wars of the Diadochi, Stasanor remained neutral, however after the Babylonian War of 311–309 BC, Margiana came under the control of Seleucus I Nicator. In c. 280 BC, Margiana was devastated by the nomadic Parni tribes and several cities were destroyed. Seleucus responded by sending his general Demodamas to repel the nomads. Under Seleucus' successor, Antiochus I Soter, the oasis of Alexandria in Margiana was surrounded by a wall over 300 km long and the city was re-built and re-founded as Antiochia in Margiana as the capital of a separate satrapy of Margiana in an effort to secure communications and trade routes from Antiochus' capital in Mesopotamia to the far east. Margiana was successfully defended by Diodotus, the satrap of Bactria, against an invasion by the Parni in c. 239/238 BC. The invasion demonstrated that Seleucus II Callinicus was unable to