The "temporal-focus hypothesis" claims that whether people conceptualize the past or the future as in front of them depends on their cultural attitudes toward time; such conceptualizations can be independent from the space-time metaphors expressed through language. In this paper, we study how Chinese people conceptualize time on the sagittal axis to find out the respective influences of language and culture on mental space-time mappings. An examination of Mandarin speakers' co-speech gestures shows that some Chinese spontaneously perform past-in-front/future-at-back (besides future-in-front/past-at-back) gestures, especially when gestures are accompanying past-in-front/future-at-back space-time metaphors (Exp. 1). Using a temporal performance task, the study confirms that Chinese can conceptualize the future as behind and the past as in front of them, and that such space-time mappings are affected by the different expressions of Mandarin space-time metaphors (Exp. 2). Additionally, a survey on cultural attitudes toward time shows that Chinese tend to focus slightly more on the future than on the past (Exp. 3). Within the Chinese sample, we did not find evidence for the effect of participants' cultural temporal attitudes on space-time mappings, but a cross-cultural comparison of space-time mappings between Chinese, Moroccans, and Spaniards provides strong support for the "temporal-focus hypothesis." Furthermore, the results of Exp. 2 are replicated even after controlling for factors such as cultural temporal attitudes and age (Exp. 3), which implies that linguistic sagittal temporal metaphors can indeed influence Mandarin speakers' space-time mappings. The findings not only contribute to a better understanding of Chinese people's sagittal temporal orientation, but also have additional implications for theories on the mental space-time mappings and the relationship between language and thought.