It is widely assumed that there is a natural, prelinguistic conceptual domain of time whose linguistic organization is universally structured via metaphoric mapping from the lexicon and grammar of space and motion. We challenge this assumption on the basis of our research on the Amondawa (Tupi Kawahib) language and culture of Amazonia. Using both observational data and structured field linguistic tasks, we show that linguistic space-time mapping at the constructional level is not a feature of the Amondawa language, and is not employed by Amondawa speakers (when speaking Amondawa). Amondawa does not recruit its extensive inventory of terms and constructions for spatial motion and location to express temporal relations. Amondawa also lacks a numerically based calendric system. To account for these data, and in opposition to a Universal Space-Time Mapping Hypothesis, we propose a Mediated Mapping Hypothesis, which accords causal importance to the numerical and artefact-based construction of time-based (as opposed to event-based) time interval systems.