From Nysa they came to a region called Daedala.[231] The inhabitants had deserted their habitations and fled for safety to the trackless recesses of their mountain forests. He therefore passed on to Acadira, which he found burned, and like Daedala deserted by the flight of the inhabitants. Necessity made him therefore change his plan of operations. For having divided his forces he showed his arms at many points at once, and the inhabitants taken by surprise were overwhelmed with calamities of every kind. Ptolemy took a greater number of cities, and Alexander himself those that were more important. This done, he again drew together his scattered forces. Having next crossed the river Choaspes,[232] he left Coenus to besiege an opulent city—the inhabitants called it Beira[233]—while he himself went on to Mazaga. Assacanus, its previous sovereign, had lately died, and his mother Cleophis now ruled the city and the realm. An army of 38,000 infantry defended the city which was strongly fortified both by nature and art. For on the east, an impetuous mountain-stream with steep banks on both sides barred approach to the city, while to south and west nature, as if designing to form a rampart, had piled up gigantic rocks, at the base of which lay sloughs and yawning chasms hollowed in the course of ages to vast depths, while a ditch of mighty labour drawn from their extremity continued the line of defence. The city was besides surrounded with a wall 35 stadia in circumference which had a basis of stonework supporting a superstructure of unburnt, sun-dried bricks. The brick-work was bound into a solid fabric by means of stones so interposed that the more brittle material rested upon the harder, while moist clay had been used for mortar. Lest, however, the structure should all at once sink, strong beams had been laid upon these, supporting wooden floors which covered the walls and afforded a passage along them.[234]