ruler of a district
• (n.) The ruler or principal man in a place or country; the governor of a toparchy.
To'parch noun [ Latin toparcha , Greek ...; ... a place + ... to govern, to rule.] The ruler or principal man in a place or country; the governor of a toparchy. « The prince and toparch of that country.» Fuller. 
toparch The ruler or prince of a small district, city, or petty state; a petty “king”.