I am not asking about military strategy, but about the process of turning military victory into political control. A quick look at a map shows that there were significant areas of land that Alexander's did not march through but still gained control of. How was Alexander (or any ruler/empire during this era) able to secure effective control over these large areas after military conquest, or did they not? Was it a simple matter of taking the administrative capital of a region or were there more efforts required to gain an effective control over the people living in these territories?
It would be more accurate to say that Alexander conquered the royal road of the Persian Empire rather than Persia itself. He also dealt with numerous rebellions and had to replace most of his satraps two or three times. Obviously it took a colossal effort - Alexander famously destroyed predatory hill tribes that had been charging tolls and making trouble for centuries in just a few days - but it fragmented immediately after his death.
A more important long term consequence was the accelerated hellenization of the near east.
