This Dragon Ball has quite a history. It is said that when Han Gaozu killed the white snake, he found it inside the snake's belly. It has always been a significant treasure of the Inner Court.
Afterwards, when the Han family's kingdom fell, it was acquired by Qian Taizu.
Upon obtaining it, he used the Dragon Ball to create this sanctuary for his descendants.
This sanctuary employs the National Fortune defense system, which Taizu understood well. If the nation survives and the monarch is assassinated, there can still be rescue. But if the nation falls, saving the monarch becomes unnecessary.
So the idea at the time was that as long as there is National Fortune, this pagoda would be very difficult to breach.
