Around 305 BCE, Chandragupta Maurya fought and reached a settlement with which Hellenistic ruler?

As part of the settlement with Chandragupta, Seleucus I received 500 war elephants. These elephants later strengthened Seleucid forces and are associated with the victory at Ipsus in 301 BCE. This question belongs to the political, religious and diplomatic history of the Mauryan age. A sound answer requires matching the ruler, person, place, title or event with its correct chronological and documentary setting. Mauryan history is reconstructed from several different bodies of evidence: Ashokan inscriptions, archaeological remains, the Arthashastra tradition, Buddhist and Jain narratives, Puranic genealogies, and Greek or Roman accounts. These sources were produced at different times and for different purposes, so their claims should not automatically be treated as identical in reliability.