Satrap:
(in the past) someone who governed a province (= political area) in ancient Persia [Cambridge Dictionary]
Noted in “Trump refuses to learn the lessons of World War II,” Max Boot, WaPo:
Those were farsighted decisions, but the postwar order was also deeply flawed. The Red Army occupied Eastern Europe, turning the region into a Soviet satrapy for more than four decades. Joseph Stalin’s troops also advanced into Manchuria, China’s industrial heartland, helping speed Mao Zedong’s victory in China’s civil war.
