What would be the impacts on an area of land that remains sunny throughout the night?

I am thinking about a medieval European styled story, but with this very strange anomaly of varying extent that goes on forever. No one knows why it’s this way and has been this way for generations and what the limits are. It goes over a roughly defined area with the border around it being ‘half sun’ at night.<br><br>What are the result of the environment around this area after a while? I’m thinking it would be warmer than the rest of the country first of all, attracting a lot of wildlife that is used to warmer climates. What about plant life, and the water cycles? Are there any effects on human psychology or culture?