Two new species of fossil hamsters (Cricetinae, Cricetidae) collected from early Pliocene sediments (similar to 4.4 Ma) in the Zanda Basin, southwestern Tibet (China), demonstrate greater past diversity among cricetines in the hinterland of the Tibetan Plateau within the Himalayan Range (beyond the previously known 'Plesiodipus' thibetensis from the late Miocene of the Gyirong Basin). The occurrence of Nannocricetus qiui, sp. nov., in the Zanda Basin indicates a dispersal of Nannocricetus from its center of origin in northern and northwestern China and the Mongolian Plateau, into the hinterland of the high-elevation Tibetan Plateau and subsequently into the Himalayan Range. The new taxon Aepyocricetus liuae, gen. et sp. nov., possibly represents a specialized (and endemic) Neogene hamster from the Tibetan Plateau. The dispersal of these hamsters into the high-elevation portions of Tibet during the early Pliocene contrasts with the hypothesized biogeographic shift of several large mammal lineages out of Tibet. The absence of Aepyocricetus and Nannocricetus from adjacent portions of the south slope of the Himalayans (and the Siwalik Hills in India and Pakistan) further implies that the Himalayan range functioned as a dispersal barrier for these small mammals by the early Pliocene.