Imperial Government
Imperialism
noun, の adjective
Sovereign government and Politics are those who are part of the imperial government. This type of government is imperialism. Of course, back in the day there weren't as many sovereign governments out there, so imperialism is the one that fits the bill in this word's case.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
ローマ帝政時代、皇帝はその村の人達に目をつけていました。
In the time of the Roman Empire, the emperor was keeping an eye on the village people.