Mammals are followers of the reptiles in the evolutionary history of the planet. Warm-blooded creatures, they inhabit almost all spheres of the earth, even some of the coldest regions. At the tail end of the reign of the dinosaurs, small mammals such as rodents had already been evolved. The catastrophe that befell the dinosaurs was not able to effect these animals as substantially. Subsequently, they developed into the various species that we see around us today.

There are reportedly up to 174 mammal species (including yet to be published information from PMNH). Some estimates suggest that there are 188 species (The Nature of Pakistan).

Palaearctic species have either reached the country from Iran via southern Balochistan (southern route) or from Central Asia through the Himalayas and Hindu Kush (northern route). The Indo-malayan species also seem to have entered by two main routes; the coast, mangroves and dry hinterland and the southern slopes of the Himalayas. Species with Ethiopian affinities entered thorough the southern coastal belt.