Answer and Explanation:
I'm not sure of what is being asked here but I'll explain based on clues given: "particular era" and "sphere of influence".
Sphere of influence has to do with a state's influence or level of control over territories outside it's borders. It is mostly used with imperialism which is claim of rights and privileges over a large or great number of foreign territories for purposes of trade, military or investment purposes.
In history, a good number of imperialist governments in their different eras have risen and fallen with the most recent being modern colonialism, the Age of Discovery/Age of European Colonisation,started about 4 centuries ago by Portugal in their conquest of Morocco.
