To what extent did internal and external factors cause the dissolution of
the Persian Empire.

Competition for the throne, economic situation and wars with the roman empire.

Explanation:

Internal factor that is responsible for the dissolution of  the Persian Empire is the competition for the throne and economic situation of the empire while the external factors that causes the dissolution of  the Persian Empire is the wars that were fought with the roman empire and defeat gained by the Persian empire. These wars weaken the economic as well as military situation of the Persian empire that is responsible for the dissolution of  the Persian Empire.

answer; i believe its (cpr);

herodotus taught this. herodotus was an ancient greek historian who was born in halicarnassus in the persian empire. he is known for having written the book the histories, a detailed record of his "inquiry" on the origins of the greco-persian wars.