Mammals represent one of the best studied group of animals in the world; however, the taxonomy of several small-sized taxa remains lagging behind, particularly in regions that are short of extensive exploration and systematic revisions. It is worrying that the team of taxonomists largely shranked in recent years even though there are a large number of taxa remaining poorly explored and unstudied. We present one example for the necessity of a comprehensive revision on these animals. The N. confucianus species complex (NCSC) is one of the most common and dominant, but taxonomically ambiguous, small mammal taxa in southeast Asia and China. More than 20 species or subspecies had been described in historical literature. Based on extensive sampling and integrating information from molecular data and morphological data, we verified their distribution range and tested the genetic divergence, morphological differentiation among different species, and subspecies. Distribution of molecular voucher specimens revealed previous studies largely overestimated the distribution of N. confucianus with a large number of misidentifications in the literature and museum collections. Morphological analysis demonstrated significant divergence amongst genetic clades and geographical populations, highlighting quick diversification of these taxa. Taxonomic revision modified the species status of several taxa and established two new species from Tibet and China.