Okay, so like in the olden days a really long time ago, there were people who were in charge of things. They were called hierocrats. This was kind of like being the boss of everything. But it was different than being a king or a queen.
Hierocrats were in charge of all the important things that had to do with religion. That means they were in charge of churches, temples, and other places where people went to worship. They were the ones who decided what people should believe and what rules they should follow.
Sometimes hierocrats would tell other people what to do. They would give orders to kings and queens, and even to regular people like farmers. This was because they were supposed to be really smart when it came to religion.
Hierocracy was when the people in charge were hierocrats. So if a country was run by hierocrats, that meant they were making all the decisions about religion and everyone else had to follow along. It was kind of like one big church where everyone had to do what the hierocrats said.
In medieval times, many countries were ruled by hierocracies. But over time, things changed and people started to believe that everyone should be able to make their own choices about religion. So hierocracies started to disappear.