This study argues that a territorial anxiety has been plaguing Sri Lankas ethnic relations for decades. This anxiety continues to haunt Sri Lankas politics even since the civil war ended. To illustrate the multiple ills this anxiety produces, we provide an ethnographic case study of the politics of boundary demarcations of local administrative units in eastern Sri Lanka, more specifically the controversy around Koralai Pattu Central Divisional Secretariat (D.S.) division (known as KPC) in Batticaloa District. By tracing the history of administrative boundary demarcation and ethnic segregation in the region, our study shows that administrative boundary demarcations are used as an attempt to purify administrative (and political) entities into ethnically homogenous territorial containers. This politics of purification produces unsolvable contradictions. The case of KPC reveals lessons not only for Batticaloas politics but for boundary demarcation politics for administrative or electoral purposes in Sri Lanka and South Asia more broadly.