In this paper we argue that historically emerging frontiers of conservation pave the way for continuous territorialization. Drawing on a concrete case in the Selous-Niassa Corridor in Southern Tanzania, we show how a frontier emerged in form of community-based conservation and decades of consecutive projects through continuous acts of territorialization through mapping and boundary making ensured that conservation is beyond questioning despite failures in the processes of demarcating, controlling and managing conservation as a socio-spatial intervention. Whereas the failures produce conflicts and confusions on the ground, we argue that in the context of a conservation frontier the gap between the ideal and reality is used to legitimize continuous interventions by relying on technical expertise rather than political dialogue. While such top-down territorialization by community-based conservation inevitably remains partial and contingent, conservation is nonetheless a powerful and resilient project that transforms communal landscapes into conservation territories with little room for public debate.