Heping Mountain was not the only border between Dong Lang and Wu Li. Apart from that snow mountain, there was another border between the two empires, and that was the forest that separated the two lands.
It was like when Dong Lang was under Shao Yaoting's coup when Bai Chen and the others tried to help Emperor Bai Guowei by infiltrating the border through the forest. At that time, Wu Jinhai was not with them, and the situation was different because the red-robed man was with them today.
It was also Wu Jinhai's decision to enter Dong Lang through Heping Mountain instead of going into the forest. He said that he was more familiar with the mountain because he used to live close to the snow mountain, and that was why it was the route that they chose today.
"You said you still live in your old palace even though you are now the Crown Prince of Dong Lang, right, ChenChen?" Casually, Wu Jinhai asked Bai Chen who was mounting another horse next to him.