 But once Emperor Xiaowen's sinicization campaign began in earnest, military service, particularly on the northern border, was no longer considered an honorable status, and traditional Xianbei warrior families on the northern border were disrespected and disallowed many of their previous privileges; these warrior families who had originally been held as the upper-class now found themselves considered a lower-class on the social hierarchy.Rebellions broke out on six major garrison-towns on the northern border and spread like wildfire throughout the north.These rebellions lasted for a decade.