His rule will last from the time he becomes king to the time he passes or gives up his throne.
From the point of vies of this place (i.e. for the people who stayed in the place) this is called emigration: when people leave the country, it's called a mass emigration.
From the point of view of the place where this person settles down, this is called immigration and this person is an immigrant
It's important to know how a person who experienced the oppression feels.