Separation of power is a modern democratic principle that was influenced by the ancient Greek and Roman idea. This is because, during their era, they were able to practice something similar.
For example, the Romans had separation of powers where there is a Senate chamber who are the people's representative and helps to decides on the matters of the region, the Emperor who rules the people. And, lastly, the Priests and Priestess who intercedes for the country. (Serves as connection between the gods and the people in important aspect like going to war, famine or planting season)
