The invader won the battle and Darius, together with a part of his army, retired to Ecbatana (modern Hamadan), the capital of Media. Meanwhile, Alexander advanced to Babylon, Susa, the Persian gate, and Persepolis, where he spent the winter. In the spring of 330, he proceeded to the north, hoping to fight a final battle with Darius.
The Persian king had been hoping for reinforcements, which did not arrive. He decided to go to the eastern part of his disintegrating empire, where he could find new troops in Bactria, the satrapy of his relative Bessus, the mathišta (intended successor). However, the Persian commanders no longer trusted the qualities of their king. When he passed through Rhagae and the Caspian Gate, moving along the Silk road to the east, the officers arrested Darius. Several days later, Alexander arrived; Bessus and his men panicked; finally, Satibarzanes and Barsaentes, the satrap of Arachosia and Drangiana, killed Darius. It was mid July 330.
The officers and the remains of their troops returned to their satrapies - Bessus, the mathišta, now being king. Alexander occupied Hyrcania, and continued to the east, to Susia (modern Tus, near Mashad). Here, the conqueror showed himself for the first time in an oriental dress, in an attempt to win the hearts of the Iranians. One of those who believed that business could be done with Alexander, was Satibarzanes, who came to Susia and announced his surrender.
This was an important success for the Macedonians. They wanted to attack Bessus, who was in Bactria, and could now proceed through the Kara Kum desert. After the surrender of Satibarzanes, Aria, on their southern flank, was secure.Or so they thought. They were already marching to Bactria when they heard that Satibarzanes had revolted. We don't know why, but he must have had sound reasons. According to the Zoroastrian religion, the god Mithra had ordered that people should keep promises, even if this promise had been made to an enemy. We don't know for certain whether Satibarzanes was a Zoroastrian or not, but similar ideas were common in ancient Iran.
Alexander was forced to return (October 330), and covered no less than 110 kilometers in two days. The only thing Satibarzanes could do, was flee. With his cavalry, he went to Bessus. Meanwhile, thousands of Arians found a refuge on a mountain top, which the Macedonian commander Craterus was besieging. He gave the honor of finishing the siege and taking the fortress to Alexander, who was able to set the platform on the mountain top, which was covered with trees, afire. Many Arians threw themselves down from the rocks.
A second Arian bulwark was the capital, Artacoana. Again, Craterus began the siege, and Alexander finished it. In the neighborhood, he built a new city called Alexandria in Aria; it is identical to modern Herat in western Afghanistan.
A month had passed since Satibarzanes had started the revolt. Now, it was too late for Alexander to cross the Kara Kum, because by now, Bessus had prepared an army. This forced the Macedonians to go to the south, to Drangiana, where they could spend the winter.
When Alexander had arrived in the north of this satrapy, he heard that Satibarzanes had returned to Aria. Alexander sent back his officer Erigyius and the Iranian Artabazus, the father of his mistress Barsine. What happened in the winter of 330/329 is not entirely clear, because our sources focus on the king, not on his deputies. Yet, it is certain that Erigyius killed Satibarzanes in single combat in the spring of 329.