The core Asian members of the genus ranged from the Indian subcontinent to Southeast Asia, and are thought to have had an aquatic ecology similar to that of the living common hippopotamus.

[2] The uncontroversial, core Asian members of the genus most closely related to the type species H. sivalensis first appeared around 6 million years ago, during the latest Miocene and were widespread throughout South and Southeast Asia, with the oldest records coming from the Siwalik Hills of the northern Indian subcontinent.

In comparison to Hippopotamus, the mandibular symphysis is much more robust, the canine processes do not extend laterally outwards, and the molar teeth are lower crowned.

The more slender and less massive postcranial skeleton compared to H. amphibius also suggests that Hexaprotodon was less adapted to walking in mud.

[5] The last known populations survived on the Indian Subcontinent to the very end of the Pleistocene,[4] with among the latest dates being around 16,467–15,660 cal years Before Present from bones found in the Narmada River valley in central India.