When Chu Nan was thinking about the boundary of Jiuyou training area, he thought of the field of Emperor Wu, the field of wuzun, the defense aperture of magic weapon, the defense array of large array, and the 12 minute realistic phantom battlefield deduced by sand table!

after careful consideration, Chu Nan had some feelings. The current border is similar to the defensive aperture, but it's much bigger and more powerful. Moreover, the border can not only prevent the outside people from entering, but also prevent the inside people from rushing out, and make the outside people not know what happened in the border.

as for Chu Nan's silent entry...