[2] The Ogooué River Valley is much less forested than its surroundings, making an open landscape that may have been used as a corridor and migration route from the coast to the interior of Africa.

[1] Later, when iron-working appeared in the valley around 2,000 years ago, the hilltop villages became larger, with nearby iron furnaces, and agriculture began to flourish.

Although over 1600 petroglyphs have been discovered dating from around the time of the beginning of iron-working, it appears that the valley was abandoned sometime between 600 and 1200 AD, before being repopulated by the present-day Okanda people in the 14th and 15th centuries.

Although the terrain is mostly monsoon forest, in the north the park contains the last remnants of grass savannas created in Central Africa during the last ice age, 15,000 years ago.

[6] The park also provides critical habitat for the leopard, protecting healthy populations of its prey species including the red river hog, African forest buffalo, and cane rat.