What factors would or circumstances would have made conquering and ruling such a vast empire difficult?

Some factors or circumstances that would have made conquering and ruling such a vast empire was, Getting past guards and enemies to try  to conquer,since the empire was so vast,you would have to deal with battling hundreds or thousands of people,putting your life and others in danger.

the answer would be in this answer. someone already asked the question.  

there are no options provided but you can choose among the following gender-neutral pronouns: zir, hir, eir, vis, tem, eir.

in the normal course of maintaining a pronoun-antecedent agreement, we could have used the words his or her but since we are also required to use gender-neutral language, we need to replace it with its equivalent gender-neutral pronoun.