Tusi are the hereditary leaders in ethnic minority areas. If there is no accident, their families will rule that place for generations.
Most of the dynasties in China turned a blind eye to these areas, and the central authorities gave them an official name, but they didn't give money and food, so long as they didn't rebel and stabilize.
But sometimes, after the rebellion is suppressed, the local officials will be changed to floating officials (officials can't be in power in one place for too long).