Bu Pass (Chin: "Wu Pass") is the southern national gate on par with Kankoku Pass. Surrounded by a large mountain range, it protects Qin's Capital of Kanyou from its neighbors to the south.
The southern path that Bu Pass protects has many stretches of steep inclination that make it unsuitable for moving large armies, as well as the strong defenses of the outposts along the way, meant that enemies scarcely ever chose it. However, it is possible for a small army to traverse the mountain undetected from Kankoku Pass to the middle of Bu Pass if sent in piecemeal. This was seen during the Coalition Army Invasion and lead to the Battle of Sai.