This article explores the meanings of infrastructural changes resulting from the Corredor Interoceánico del Istmo de Tehuantepec (CIIT) infrastructure project for the cultural survival of Indigenous peoples resident in the Tehuantepec Isthmus region through the lens of ontological justice. Based on interviews with affected residents in the states of Oaxaca and Veracruz, this research finds a strong desire for cultural continuity, collective life projects, Indigenous languages, cultural identities, beliefs, spirituality, established political and legal systems, and a solidarity economy. Contemporary megacorridors function as circulatory infrastructures that shift the life-reproducing benefits from territories elsewhere, thereby effectively imposing integration and assimilation of Indigenous peoples, Afrodescendant and comunidades equiparables into the dominant modern/colonial extractivist one-world world, and provoking mundicide. This article provides an empirical case for the urgency of recreating an ontodiverse world order that can guarantee the futurity of other ways of world-making.