Philistia is a place that existed a really long time ago, kind of like how mommy and daddy's grandparents lived a long time ago. It was located in a part of the world called the Middle East, which is far away from where we live.
In Philistia, there were people called the Philistines who had their own way of life and beliefs, kind of like how different families have their own way of doing things at home. They were known for being very good at making things out of metal, like swords and shields.
The Philistines lived in cities that they built themselves and they were very strong and difficult to defeat in battle. In fact, they often fought with people from another group called the Israelites, who were the ancestors of the Jewish people.
Even though the Philistines were strong fighters, they weren't always nice to the Israelites and there were many stories of fighting between the two groups in a book called the Bible. Eventually, the Philistines were defeated by the Israelites and Philistia stopped existing as a place.