Final answer:
Chandragupta Maurya took advantage of the power vacuum left by Alexander the Great's retreat to establish the Mauryan Empire and defeat the remaining Hellenistic forces in Northwestern India.
Step-by-step explanation:
The relationship between Chandragupta Maurya and Alexander the Great was an indirect one. Chandragupta did not directly work with or encounter Alexander. Instead, following Alexander's retreat from the Indian subcontinent and the subsequent power vacuum he left behind, Chandragupta seized the opportunity to establish and expand the Mauryan Empire. He went on to defeat the forces that had been left behind by Alexander in the Northwestern regions of India, after Alexander's troops, exhausted and unwilling, forced him to abandon his plans for further conquests.