The reform era around the turn of the century in Indonesia has been followed by a revitalization of local claims to political authority and natural resources on the basis of adat and indigeneity. In May of 2013, the Constitutional Court acknowledged indigenous ownership of forest territories and declassified them from State-owned forest zones without further conceptualizing the notion of indigeneity and its relation to land tenure and territorial conflicts. Drawing on a historical review of the adat discourse, this paper demonstrates how Dutch scholars during the colonial time have supported a definition of indigeneity based on territorialisation. Using a case study from the interior of Kalimantan, we provide evidence that privileging indigenous communities based on the notion of territoriality and prior occupation of the land, supported by a colonial definition of adat rights tends to exclude right-holders who do not necessarily fit clear territorial niches. This administrative practice of essentializing the social structuring of the landscape matches the requirements used in the context of REDD+ but ignores the fact that social and territorial boundaries of ethnic groups are permeable and dynamic due to social-political interactions which create contention and conflict especially in the context of the recent introduction of carbon rights and benefit sharing under the context of REDD+.