The four surrendered tribes, including the Nadu Department, were located to the east, south, west, and north of the oasis. The Nadu Department itself was in the northern part, at the foot of Yin Mountain. A century of strategic suppression by the Earl of North Border had been so effective that even his 'puppet' allied barbarian troops had developed a confident air. Especially in the last twenty years, the other barbarian tribes had rarely launched any counterattacks against the Earl of North Border, leading the Nadu Department's people to become complacent.
Naduo Jiayang, the "Junior Chief" of the Nadu Department, had assigned fewer than a thousand of his personal guards to a pasture within their territory. He hadn't publicized this, so the tribe's perimeter security remained as lax as ever.
