What is the permian sea How do we know it existed?

The Permian Sea refers to a shallow marine environment that existed during the Permian period, roughly 299 to 252 million years ago, covering large parts of what is now North America and Europe. Evidence of its existence is found in geological formations, fossil records, and sedimentary rock layers that contain marine fossils, indicating the presence of ancient marine life. Additionally, the distribution of certain types of rocks and minerals associated with marine environments supports the idea of this expansive sea during that era.