For the last decades, the authors have carried out detailed investigation on the Neogene sequence around the Tianshui region and found that the Neogene deposits at Yanwan (105°34’E, 34°58’N), 15.5 km northwestern to Qin’an County in Tianshui Basin, contain abundant mammal fossils. Fossil assemblage features of Yanwan site suggest that the Tianshui region was dominated by subtropical savanna environment quite suitable for the inhabitation of large mammals. Situated at the transitional region from eastern monsoon region to Qinghai-Tibetan Plateau region, the Yanwan fauna from upper fossil layer might be a representative Hipparion fauna site between North China and Qinghai-Tibetan Plateau.