Traveling Through Cao Anmin, the Three Kingdoms Are Not Easy to Mix With

After traveling through time and becoming Cao Anmin, why can't he be told that he is in Wancheng this time? The system does exist, but it is trigger-type, and it has the final say whether it comes out or not. The Three Kingdoms are not easy to mess with. If you follow history, you will die. If you don't follow history, you don't know how to follow. I have no choice but to risk my life. At least solve the problem of Wancheng first.