The Krau Wildlife Reserve, which is the second largest after the national Park, was established in 1923. Originally covering 55,159 hectares, it has now grown to 76,000 hectares following a series of gazettements and degazettements. The latest move has turned the area into what is now known as Pahang's Bio-Valley, where logging and poaching are prohibited. Comprising forests estimated to be at least 1,000 years old, it is located east of Gunung Benom in the district of Temerloh.

The area is drained by Sungai Krau, Sungai Lompat and Sungai Teris. The altitude in the reserve ranges from 43 meters in Kuala Lompat to 2,107 meters at the peak of Gunung Benom. The place was originally established to protect wildlife, especially the Seladang (wild ox). It is home to the Jah Hut and Siwang tribes of the Senoi aboriginal group.

The ecosystem spreads across a broad spectrum of unspoiled tropical rainforest habitats, home to wildlife such as the endangered rhinoceros, several species of deer (including the napuh), antelope, and seladang. Standing proud in this reserve is Malaysia's sixth tallest mountain, Gunung Benom at 2,107 meters above sea level.

Gunung Benom is one of the most isolated mountains in the central plain of Peninsular Malaysia and is predominantly made up of Jurassic-Cretaceous granite surrounded by Permian-Triassic marine sediments. It is rich in flora and fauna, which have not been explored in detail.

The crystal clear waters of Sungai Lompat  and the undisturbed primary forests are testimony to the area's pristine condition that perpetuates the healthy growth of lowland and hill dipterocarp forests. Trees, including the Shorea Pauciflora species, comprising the meranti, seraya and lauan, laurel, oak, mosses, orchids, pitcher plants and ferns make up the typical landscape.

The diversity of flora and fauna is recognised by scientists and researchers, prompting the use of the eastern section of the reserve at Kuala Lompat as a natural laboratory to study the behavioural patterns of primate species like gibbons, bats, birds and forest plants.