This article explores an extreme case of sociospatial fragmentation on the peri-urban edges of Jakarta, where a gated residential development has fully surrounded a trio of villages, or kampungs. Based on 19 site visits between 2018 and 2024, including interviews with stakeholders, observations of residents’ spatial practices, and maps and site studies of the built environment, we ethnographically examine the construction and transformation of the intervening border, a three-meter-high concrete wall designed to achieve the absolute separation of the adjoining enclaves. Over time, however, the wall has become incrementally more porous, allowing new forms of connection and exchange. Through the conceptual framework of assemblage, including its constitutive axes of content–expression and deterritorialization–reterritorialization, we analyze the wall as a spatial means of political contestation. The spatial politics of the border wall emerges from the slippage between its content and its expression, producing moments of deterritorialization and reterritorialization that make possible new relationships. While enclave borders initially produce the division between gated community and kampung by materially inscribing relations of power and exclusion, they also make possible the political contestation of that division through the production of unanticipated relations with new and varied contexts and actors.