At first, they hadn't noticed anything amiss, but after Emperor Jianwu and his companions had traveled along this forked path for some time, the various oddities that appeared made Emperor Jianwu and his companions realize that this path they had chosen was very likely a dead-end. Travelling along such a dead-end was certain death; in fact, it was tantamount to courting a fate with no return.
Emperor Jianwu and the princes continually used the Sound Transmission Skill to engage in frequent discussions. Shortly after entering this forked path, they finally came to a consensus. They decided to stop advancing and instead, the front of the group would become the rear, and the rear would become the front as the entire group turned around. They decided to head back, disregarding anything else, with the priority being to exit this forked path and return to safety, and then to choose another path from there.