Follow up question : to what extent should we believe accounts of historians that must have been in Alexander’s retinue? Or am I mistaken About it?

Edit : I can’t grammar apparently.

Also I forgot to mention this in original post, hope this post may stand. But it is historically accepted that the maurya dynasty is not contemporary of Alexander. Nanda dynasty ruled magadha at the time of Alexander’s invasion of northwestern Indian subcontinent. It was during Seleucus’ time that Chandragupta ( named Sandrocottus ) maurya ruled.

Always lying in wait for the neighboring nations, strong in arms and persuasive in council, he 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 [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.

— Appian, History of Rome, The Syrian Wars 55