Which Mourya King entrusted the government of a rich province to a Yavana officer?

Ashoka appointed a Yavana (Greek/Ionian) officer named Tushaspha to govern the rich province of Gandhara (northwestern frontier). This is evidenced by his edicts and historical records. The Mauryas maintained good relations with Seleucus, and Greek officers were employed in administration, especially in border regions with Greek populations.