Merovingians were a group of really important people who lived a very long time ago. They were in charge of a place that we now call France.
Now, imagine you have a big family with a lot of people in it. The oldest person in your family is in charge of everyone else. This is kind of what the Merovingian family was like. They were the oldest and most important family in all of France.
These people were called "Merovingians" because that was the name of the first big boss in their family. It's kind of like how your last name is your family's name too.
A long time ago, the Merovingians were really good at running their big family and everyone who lived in France looked up to them. But then, things started to change. Other groups of people started to want more power and they didn't like that the Merovingians were in charge.
Eventually, a group of people called the Franks took over and the Merovingians didn't have as much power anymore. But even though they weren't in charge anymore, people still remembered them as being really important in the history of France.