The Wannian Palace Was Built with Dirt

I have a portal that allows me to travel freely to any dynasty. I want to travel to ancient times, and during my travels I personally witness the life of various dynasties. To witness every historical event, what is each class thinking? What are the reasons for this historical regret? Why did everyone make such a decision, and what kind of real-life problems led to the occurrence of these regrets and different views on the issues in history books. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.