the sphere or area over which someone holds control or within which they operate;
e.g. This incident is within my fief, so I will be the one to address it.
(noun)
(historical, legal) an estate of land that is held by a person but owned by a feudal lord, which they are allowed to hold under the condition that they will serve the lord;
e.g. He maintained his fief well and paid his dues on time.