What is it called when one power controlled the trade exports of another?

Answer;

-Sanctions

Explanation;

-A sanction is a penalty levied on another country, or on individual citizens of another country. It is an instrument of foreign policy and economic pressure that can be described as a sort of carrot-and-stick approach to dealing with international trade and politics.

-The immediate impact of an import sanction on the target country is that the country's exports are not purchased abroad. Depending on the target country's economic reliance on the exported good or service, this could have a crippling effect.

-The sanction might cause the sort of political and economic instability that results in a more totalitarian regime, or it can create a failed state due to a power vacuum. The target country's suffering is ultimately borne by its citizens, who in times of crisis may solidify the regime in charge rather than overthrow it.