From montane rainforests to the largest area of pristine lowland dipterocarp forests left in Malaysia, Peninsular Malaysia is home to a rich flora and fauna. The small mammal assemblage of this region is very similar to Sumatra in terms of species richness and the different families that occur here, and the numbers of species within them. It is dominated by murid rodents (27 species) and squirrels (27 species). Of these, nine species are globally threatened, including examples such as Greater Marmoset Rat, Rajah Sundaic Maxomys, Cameron Highlands Niviventer, Whiskered Flying Squirrel, Vordermann's Flying Squirrel and Smoky Flying Squirrel. This is the only SMSG Key Region in which moles (Talpidae) occur with two species, Kloss's Mole and Himalayan Mole. There are no AZE trigger small mammal species within this Key Region.

Logging, conversion for agriculture, road construction and urban development are the primary drivers of forest loss and degradation in this area.

One of the largest protected areas in Southeast Asia, the Taman Negara National Park, covers a sizeable section of this region.

With just 5 Data Deficient species, most described species in this Key Region are known well enough to assess their extinction risk. But our knowledge levels of most species beyond this are very limited.