Although of negligible economic interest, the Black River Basin during the French colonial period enjoyed special administrative status as a military territory. The region's patchwork pattern of ethnolinguistic groups as well as problems of distance and strategy led the colonizer to renew the autonomy of the muäng, or Tai polities. Among principal Tai clans, the Đèo of Lai Châu exemplified political resilience: pursuing their own prerogatives (until 1954) by exploiting the French administrative framework. These hereditary leaders, employed as colonial scholar-officials and civil servants, were keen to combine contradictory vocations. For example, the Đèo were frontier wardens even though their ancestral muäng overlapped the border; they were tax collectors who were nevertheless involved in opium smuggling. This paper attempts to recreate an overall pattern of the constitutive elements traditionally governing the attribution and implementation of power on a local basis.