But there was nothing to conquer. If you have a wealthy and advanced country, why would you spend your time and money trying to conquest a wasteland. There was nothing beyond the Indus that was worth conquering.
You are correct, and this is where people misunderstand history.
The Mauryans never intended to conquer Afghanistan.
Let's look at this excerpt from Arrian's
Syriaca:
"Always lying in wait for the neighboring nations, strong in arms and persuasive in council, he [Selecus Nicator] acquired Mesopotamia, Armenia, 'Seleucid' Cappadocia, Persis, Parthia, Bactria, Arabia, Tapouria, Sogdia, Arachosia, Hyrcania, and other adjacent peoples that had been subdued by Alexander, as far as the river Indus, so that the boundaries of his empire were the most extensive in Asia after that of Alexander. The whole region from Phrygia to the Indus was subject to Seleucus.
He crossed the Indus and waged war with Sandrocottus [Chandragupta Maurya], king of the Indians, who dwelt on the banks of that stream, until they came to an understanding with each other and contracted a marriage relationship. Some of these exploits were performed before the death of Antigonus and some afterward."
The Mauryans did not initiate the expansion into Afghanistan. They merely gained the territories as a result of an unsuccessful invasion by the Seleucid Greeks, as the treaty which ended the conflict involved the cession of the provinces of Aria, Arachosia, and Paropamisadae (these three provinces compromise most of present-day Afghanistan) to the Mauryans in 305 B.C.E. This war occurred two decades after the conquests of Alexander, and so it cannot be said that the Mauryans won Afghanistan because Alexander "eliminated the Persians" from the region. Other sources, such as Strabo and Justin, depict a similar course of events.
