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.