Alexander now halted at Hekatompylos,[18] a place which received this Greek name from its being the centre where many roads met, and which became in after times the capital of the Parthian kings. Being joined here by the rest of his army, he prepared to invade Hyrkania, from which he was separated by the chain of mountains now called the Elburz. As the passes were beset by robber-tribes, he divided his army into three bodies. The most numerous division crossed the mountains under his own command by the shortest and most difficult roads. Krateros made a circuit to the left through the country of the Tapeirians (Taburistan), while the third division under Erigyios took the royal road which led westward from Hekatompylos to Zadrakarta.[19] The divisions on emerging from the defiles united, and encamped near the last named place, which was the Hyrkanian capital. Hither came to Alexander with three of his sons the aged Artabazos, accompanied by the Tapeirian satrap and by deputies from the Greek mercenaries of Darius. Artabazos was received with distinguished honour, both because of his high rank and the fidelity he had shown to Darius, whom he had accompanied in his flight. The satrap was confirmed in his government, but the deputies were sternly told that as the mercenaries had violated the duty which they owed to their country, they must submit themselves unreservedly to the judgment of the king. Alexander then attacked the Mardians who inhabited the lofty mountains to the north-west of the Kaspian Gates. They submitted after a slight resistance, and were ordered to obey the Tapeirian satrap.