The tribal system that governed the various nomad clans who considered themselves to be a part of the Liao state was very convoluted and relied more on personal relationships than any formalized system. In general, the more proximate a tribe was located relative to the center of the empire and the more its members had personal dealings with the emperor, the more loyal it was. At the opposite end of the spectrum, tribal confederations such as the Zubu or Tsu-Pu who were on the distant fringes of the empire tended to be significantly less reliable and more hostile to Khitan activity in their areas; frequent military expeditions were required to keep them in line.