Holy Roman Empire

The Holy Roman Empire (HRE) was a multi-ethnic complex of territories in Western and Central Europe that developed during the Middle Ages. It was initially established in 962 by Otto I, King of Germany, and lasted until 1806, when it was dissolved by Francis II (Due to napoleon), the last Holy Roman Emperor. The HRE was not a centralized state with a strong central government, but rather a loose federation of independent states, each with its own ruler. The emperor, who was elected by the princes, had little real power and was mainly a symbolic figurehead. Despite its decentralized nature, the HRE played an important role in European politics and cultural development during the Middle Ages.

HRE system
The HRE as said in the Preview was not centralized but instead had many kingdoms/duchies that elected new emperor, not all of the state had this privilege to vote for the Emperor and the one who had it were called "Electorate"